Implementation
Global Landscape
LCS implementation is expanding worldwide ([Table 2]). To date, national screening programs have been established in North America (the
United States), Asia (Japan, China, South Korea, and Taiwan), and Europe (Croatia,
the Czech Republic, and Poland). Japan is the only country where screening has primarily
occurred by chest radiology and sputum cytology until now.[29] Programs have varied in their effectiveness to reach the target population, due
in part to differences in delivery, resource allocation and capacity, and policy decisions.[30] In the United States, LCS uptake remains below 20%,[31] whereas in Croatia, it has exceeded 80%.[32]
Table 2
Global implementation of lung cancer screening
|
Country
|
Implementation stage
|
Key milestones
|
Eligible population
|
|
United States
|
Implemented nationally
|
2013: U.S. Preventive Services Task Force first recommended annual LDCT screening
for high-risk adults, based on National Lung Screening Trial (NLST) results
2015: Centers for Medicare and Medicaid Services established coverage for LDCT screening
|
Asymptomatic adults aged 50–80 with a >20 pack-year smoking history and still smoking
or quit within the last 15 y
|
|
Canada
|
Implemented in some, but not all provinces
|
2021: Ontario launched an LCDT screening program at 4 sites after an implementation
pilot
2022: British Columbia launched a province-wide LDCT screening program
2024: Nova Scotia launched a province-wide LDCT screening program
2025: New Brunswick will launch a province-wide LDCT screening program
Quebec, Alberta, Newfoundland, and Labrador have implemented pilot programs
|
Ontario: Adults aged 55–80 who have a >20 pack-year smoking history and have smoked
within the last 15 y
British Columbia: Adults aged 55–74 who have a >20 year smoking history and are still
smoking or have quit
Nova Scotia: Adults aged 50–74 who have smoked daily for 20 or more years
|
|
Japan
|
Implemented nationally, with opportunistic LDCT screening
|
1987: Japan began offering chest X-ray screening to people aged 40 and older, with
opportunistic LDCT screening
2010: Ministry of Health, Labor, and Welfare initiated a nationwide randomized controlled
trial comparing two LDCT scans vs. a single chest X-ray scan over a 10-y period in
over 20,000 adults aged 50–70 who currently or formerly smoked. Follow-up expected
to end in 2035
|
Adults aged 40 and older
|
|
South Korea
|
Implemented nationally
|
2015: A multi-society collective developed guidelines recommending annual LDCT screening
for high-risk individuals
2017–2018: Korean Lung Cancer Screening Project (K-LUCAS) conducted to assess the
feasibility of implementing a national screening program, with promising results
2019: Formal launch of national program of biannual LDCT screening, including smoking
cessation counseling
2023: Over 600,000 eligible individuals screened (∼53% uptake)
|
Adults aged 54–74 with a smoking history of >30 pack-years
|
|
Taiwan
|
Implemented nationally
|
2014: Taiwan Lung Cancer Screening for Never-Smoker Trial (TALENT) started
2022: The Ministry of Health and Welfare launched a national program of biannual LDCT
screening for high-risk populations
|
Two high-risk populations:
1. Adults aged 50–74 with a smoking history of >30 pack-years
2. Men aged 50–74 and women aged 45–74 with a family history of lung cancer
|
|
China
|
Implemented primarily in urban areas
|
2012: China launched the Cancer Screening Program in Urban Areas, which includes biannual
LDCT screening of high-risk individuals across 75 cities in 30 provinces
|
Adults meeting one of the following criteria: ≥30 pack-years of smoking and <15 y
since quitting; exposed to passive smoking at home or in the workplace for ≥20 y;
a diagnosis of chronic obstructive pulmonary disease; >1 y of regular occupational
exposure to asbestos, radon, beryllium, chromium, cadmium, nickel, silica, coal smoke,
or soot; first degree family history of lung cancer
|
|
Singapore
|
Not implemented
|
No national screening program, but the Ministry of Health recommends LDCT screening
for high-risk populations
|
|
|
Croatia
|
Implemented nationally
|
2020: Croatia became the first European country to launch a national LDCT screening
program
2023: More than 26,000 people screened, representing over 80% of the target population
|
Adults aged 50–75 with a smoking history of >30 pack-years and still smoking or quit
in the last 15 y
|
|
The United Kingdom
|
Implemented nationally
|
2011: UK began pilot trials and studies to assess feasibility and aspects of LDCT
screening, including UK Lung Cancer Screening (UKLS) pilot trial, Liverpool Health
Lung Programme, Manchester Lung Health Check pilot, Lung Screen Uptake Trial (LSUT),
West London lung screening pilot trial, Yorkshire Lung Screening Trial (YLST), and
SUMMIT study
2019: NHS England launched the Targeted Lung Health Check program, which demonstrated
efficacy to support the national LDCT screening program
2023: The UK began a national rollout of the LDCT screening program with targeted
outreach, with complete rollout expected by 2030
|
Adults aged 55–74 who are registered with a GP practice and currently or formerly
smoke are invited—eligibility for LDCT screening is then determined by model-based
risk assessment
|
|
The Czech Republic
|
Implemented nationally via pilot
|
2022: The Czech Republic launched a 5-y population pilot screening program
|
Adults aged 55–74 with a smoking history of >20 pack-years
|
|
Poland
|
Implemented nationally via pilot
|
2018: Consensus for national LDCT screening, based on pilot data
2020–2024: Poland conducted a national pilot LDCT screening program across six macro-regions
|
Adults aged 55–74 with a smoking history of >20 pack-years or specific occupational
exposures or related health conditions
|
|
Hungary
|
Assessing feasibility
|
2013–2020: First pilot conducted to demonstrate the feasibility of LDCT screening
2019–2022: Second pilot conducted to build a patient pathway
2023: Third pilot started to determine the approach for identifying high-risk individuals
and inviting them to be screened. Data expected in 2025
|
|
|
Italy
|
Assessing feasibility
|
2021: Model for Optimized Implementation of Early Lung Cancer Detection: Prospective
Evaluation of Preventive Lung Health (PEOPLHE) trial launched to evaluate the feasibility
and implementation of LDCT screening in the national healthcare system
|
|
|
Spain
|
Assessing feasibility
|
2022: Spain launched the CASSANDRA Project to explore the feasibility of implementing
LDCT screening
|
|
|
France
|
Assessing feasibility
|
2022: The French Health Authority acknowledged the efficacy of LDCT screening and
recommended a national pilot program
2025: Launch of pilot program to assess the feasibility of national LDCT screening
implementation
|
|
|
Germany
|
Assessing feasibility
|
2024: Federal Ministry for the Environment, Nature Conservation, Nuclear Safety, and
Consumer Protection issued the Lung Cancer Early Detection Ordinance, allowing providers
to offer LDCT screening
|
|
|
Belgium
|
Assessing feasibility
|
2025: Flanders will launch an implementation study on LDCT screening in Zuid-Oost
Rand Antwerpen (ZORALCS)
|
|
|
The Netherlands
|
Assessing feasibility
|
Research and implementation trials, including the 4-IN-THE-LUNG-RUN (4ITLR) trial,
are ongoing to examine aspects of LDCT screening implementation
|
|
|
Australia
|
Pending implementation
|
2025: Australia will launch a national program of biannual LDCT screening in July
|
Asymptomatic adults aged 50–70 with >30 pack-year smoking history and still smoking
or quit within the last 10 y
|
Other countries are at varying stages of implementation. In Canada, several provinces
have implemented LCS programs, while other provinces are running pilot programs.[30] Implementation in Europe has occurred slowly, despite strong evidence from NELSON
and other European screening trials and implementation studies. In September 2022,
the European Commission endorsed stepwise implementation of LCS across the European
Union (EU), and shortly thereafter, the EU Council of Ministers for Health approved
funding for LCS at the national and EU levels. The Strengthening the Screening of
Lung Cancer in Europe (SOLACE) project, which launched in April 2023, has become a
key initiative within Europe's Beating Cancer Plan. SOLACE is uniting a network of
European respiratory and radiology experts from 15 countries to enhance LCS efforts
in underserved and high-risk populations across the EU.[33] Also in September 2022, the United Kingdom National Screening Committee recommended
LCS, with a policy review outlining key priorities and requirements for implementation.[34] The UK began rolling out its nationwide targeted LCS program in 2023, with the goal
of reaching 40% of the eligible population by 2025 and full implementation by 2030.[35] Australia is launching its national screening program in July 2025.[36]
Initiatives dedicated to advancing high-quality LCS implementation include the Lung
Cancer Policy Network,[32] the G7 Cancer Alliance,[37] and the ACS National Lung Cancer Roundtable (NLCRT).[38]
Selection Criteria and Approach
No universal consensus exists on defining the population at “high risk” who is most
likely to benefit from LCS. Accordingly, the population eligible for LCS differs between
countries ([Table 2]). Even within the screening-eligible population, individual risk for developing
lung cancer varies substantially, and the benefit conferred by LCS varies according
to risk.[22] The selection criteria largely center on age and smoking history, given that lung
cancer risk strongly increases with greater age and tobacco exposure, with some variation
in the age range and thresholds for P-Y smoked and time since quit applied across
countries. Selecting individuals on fixed age and smoking history criteria alone;
however, results in including some at low risk who are unlikely to benefit from LCS
and excluding others at high risk who are likely to benefit from LCS.[39]
[40] Some countries consider screening based on other criteria. In Japan, eligibility
is based on age alone.[29] Taiwan is the first to include screening of individuals with a family history of
lung cancer who have never smoked,[41] while China is the first to include screening of individuals with a history of chronic
obstructive pulmonary disease (COPD), with specific occupational exposures, or with
a family history of lung cancer.[42] Poland has also included screening individuals with specific occupational exposures
or related health conditions.[43]
Risk-based screening is an alternative approach with the potential to improve the
balance of benefits to harms by screening fewer individuals, producing fewer false-positive
results, and detecting more early-stage lung tumors.[44] Individuals are selected based on whether their personal risk for lung cancer—calculated
using risk prediction models that incorporate age, smoking history, and various clinical
and nonclinical factors—exceeds a specified risk threshold. To date, a myriad of risk
prediction models have been proposed to estimate individual risk of developing or
dying from lung cancer within a given time window; yet, only a handful have exhibited
good performance in external validation studies[45]: the Bach model,[46] PLCOM2012 model,[47] Liverpool Lung Project (LLP) model,[48]
[49] Lung Cancer Risk Assessment Tool,[50] and Lung Cancer Death Risk Assessment Tool.[50]
Retrospective analyses consistently show that applying accurate risk prediction models
to select ever-smoking adults for screening is more effective in preventing lung cancer
deaths than applying fixed criteria on age and smoking history.[23]
[47]
[50]
[51] Studies also suggest that risk-based screening using the PLCOM2012 model can reduce lung cancer disparities, with a higher sensitivity for detecting
lung cancer in racial and ethnic minority populations and women than USPSTF criteria-based
screening.[52]
[53]
[54] However, risk-based screening can lead to comparatively modest increases in the
number of life years and quality-adjusted life years (QALYs) gained and greater overdiagnosis,
because it preferentially selects adults at the highest risk; these adults are generally
older, have more comorbidities, and thereby may benefit less due to their shorter
life expectancy and higher mortality from other causes.[51]
[55]
[56] Ideally, selecting individuals for LCS would consider both individual estimates
of risk and life expectancy to prevent the most deaths and maximize the expected life-years
gained in the population.[39]
[55]
[57] Several novel frameworks and strategies that incorporate individual risk, preferences,
and life expectancy have been developed to inform risk-based screening decisions,
although the minimum gain in life expectancy to recommend remains unclear.[55]
[58]
[59] Also under specific modeling assumptions, risk-based screening strategies appear
more cost-effective than screening based on the 2021 USPSTF criteria.[60]
Outside the United States, promising results have emerged from multiple prospective
trials and studies evaluating the feasibility and effectiveness of implementing risk-based
LCS. The SUMMIT study demonstrated the feasibility of effectively delivering large-scale
LCS to 12,773 enrolled the UK participants aged 55 to 77 who either met the 2013 USPSTF
criteria or had a PLCOM2012 risk threshold of ≥1.3%.[61]
[62] The Manchester Lung Health Check pilot was likewise successful in delivering targeted
LCS to high-risk individuals with a PLCOM2012 risk threshold of ≥1.51% living in sociodemographically disadvantaged areas.[63]
[64] In this pilot, follow-up of the screened and unscreened groups, classified based
on the PLCOM2012 risk threshold, confirmed that only a few lung cancer cases arose in the low-risk,
unscreened group.[65] The Yorkshire Lung Screening Trial (YLST) compared the performance of selecting
high-risk participants with the PLCOM2012 risk threshold of ≥1.51%, LLPV2 risk threshold of ≥5%, and 2013 USPSTF criteria.[66] The PLCOM2012 model identified the most people eligible for screening and the most screen-detected
lung cancers, and both risk models were more efficient at selecting individuals than
the USPSTF criteria.[67] While telephone risk assessment was effective in inviting individuals for LCS in
the YLST, current smoking status and socioeconomic deprivation corresponded with lower
participation.[68] Interim analyses of the International Lung Screening Trial (ILST) further suggest
that selecting ever-smoking adults aged 55 to 80 using the PLCOM2012 risk threshold of ≥1.51% is more effective than the 2013 USPSTF criteria.[69]
[70] Cost-effectiveness analyses using ILST data also show that risk-based screening
results in greater cost savings, increased QALYs, and reduced inequities in screening
access.[71] Currently, the 4-IN-THE-RUN trial is recruiting 900,000 individuals with a smoking
history of ≥35 P-Y who have smoked in the last 10 years or with a PLCOM2012 risk of ≥2.6% from the Netherlands, Germany, England, France, Italy, and Spain to
determine the optimal personalized LCS approach that incorporates comorbidity-reducing
strategies.[72]
Program Structure
In the United States, LCS programs are generally structured using a centralized, decentralized,
or hybrid approach.[17] LCS guidelines do not recommend a specific approach, but instead the approach that
aligns best with existing resources and needs of the population served. In centralized
programs, primary care providers and other clinicians refer individuals to an LCS
program, which has dedicated personnel responsible for critical program components,
including eligibility assessment, shared decision-making (SDM), tobacco cessation
management, LDCT ordering, communication of LDCT results, and management of follow-up
screening and care. In decentralized programs, ordering providers hold overall responsibility
for the entire LCS process, including specialty referral for follow-up care. At present,
the majority of LCS occurs in decentralized settings. Many programs are also hybrid,
where some but not all elements are centralized along the LCS continuum.
Centralized programs appear to be more effective, particularly in terms of adherence
to annual LCS and follow-up care, than decentralized programs.[73]
[74]
[75] Centralized programs also more commonly implement practices to support LCS before
screening is initiated.[76] Yet, the specific structures and practices of centralized programs that enhance
LCS quality and effectiveness remain unclear.[77]
[78] Limited evidence suggests that patient navigation practices, including support with
scheduling, transportation, and accessing resources to reduce barriers to care, can
improve LCS uptake and adherence, particularly in vulnerable populations.[79]
[80]
[81] Given that centralized programs require considerably more investment and resources,
further research is needed to understand which components of centralized programs
are the most beneficial and whether they could be extended into noncentralized programs.[77]
[78]
Shared Decision-Making
SDM is recommended to help patients in making informed decisions about LCS with clinicians,
considering the best available evidence on the benefits and harms of LCS and their
own values and preferences.[20] The American Thoracic Society and Veterans Affairs Health Services Research and
Development jointly advocate that SDM embrace several core principles, specifically
to “empower the patient to participate in SDM to the extent they desire,” “include
the information about LCS that the patient needs and wants to make an informed, value-based
decision,” and “avoid exacerbating population-level disparities or worsening stigma
related to smoking.”[82] For reimbursement coverage, the U.S. Centers for Medicare and Medicaid Services
mandates a documented SDM visit with a qualified healthcare provider (physician, physician
assistant, or nurse practitioner) before the beneficiary's first LDCT scan.[18] Specific visit requirements entail eligibility determination, SDM that incorporates
the use of at least one decision aid, as well as counseling on the importance of screening
adherence and of smoking cessation and abstinence, the impact of comorbidities, and
the willingness to undergo follow-up care and treatment if abnormal findings arise.
These standards have been challenging to meet in practice. Although clinicians recognize
the value of SDM, many cite major barriers to facilitating SDM, including time constraints,
competing clinical demands and priorities, limited awareness about LCS guidelines,
lack of skilled training in SDM, and insufficient resources to implement SDM.[83]
[84]
[85] Concerns have been raised about the intent and quality of SDM for LCS, given evidence
that SDM conversations are often brief, prioritize exchanging information more than
eliciting patient preferences, focus on benefits over harms, and lack the use of decision
aids.[85]
[86] Nonetheless, various decision aids, tools, and processes for SDM have been reported
to improve patient knowledge, reduce decisional conflict, show acceptability to patients
and providers, and increase LCS uptake and adherence.[87]
[88]
[89]
[90]
[91]
[92] Especially those effectively tailored to populations at higher risk for lung cancer,
such as people with HIV, may further promote health equity.[92]
[93]
The role of SDM has become even more important since the USPSTF expanded the screening-eligible
population to include individuals at lower absolute risk of lung cancer. Yet, the
optimal approach to achieving high-quality SDM in LCS remains elusive. To overcome
clinician barriers, a practical approach would have well-trained nonclinicians conduct
SDM.[94] Several effectiveness-implementation studies are ongoing to identify effective and
scalable approaches for SDM in LCS, including the TELESCOPE study that is evaluating
a telehealth decision coaching and navigation intervention delivered by patient navigators
in primary care clinics.[95]
[96]
[97] Clinicians are also open to employing more novel approaches, such as prediction-augmented
SDM tools, which provide tailored LCS recommendations according to the level of predicted
benefit.[98] Priorities outlined by the NLCRT and others to advance SDM research and implementation
in LCS include developing adaptable SDM training programs for health care personnel,
understanding how alternative screening delivery models affect SDM quality, developing
and evaluating novel SDM tools across different settings and populations, establishing
key SDM process quality measures, and investigating the utility of prediction-driven
SDM.[82]
[99]
Smoking Cessation
Smoking cessation is a necessary, but challenging component of high-quality LCS.[100] With at least 50% of all screen-eligible individuals actively smoking,[101] LCS offers “teachable moments” to reinforce smoking abstinence and to motivate and
support those who smoke to quit.[102]
[103] Of the participants in the UK Lung Health Check program who currently smoked, 44%
indicated that screening made them consider quitting, 29% indicated that it made them
attempt to quit, and 25% indicated that it made them smoke less, although only 10%
indicated that it made them seek help to quit.[104]
Among NLST participants from the American College of Radiology (ACR) Imaging Network
arm, over a third were highly addicted to nicotine and reported smoking within 5 minutes
of waking up.[105] Yet, of those participants who smoked at enrollment and underwent LCS, 73.4% received
no pharmacologic tobacco treatment, and those who were female, African American, unmarried,
and less educated were less likely to attempt quitting.[106] Other studies have similarly noted that lower nicotine dependence and lower educational
attainment correspond to less engagement in smoking cessation interventions.[107]
[108]
[109]
Model-based analyses indicate that smoking cessation confers added population health
benefit beyond LCS alone. Even with modest quit rates (e.g., 10% quit), a single smoking
cessation intervention at the initial screen can lead to fewer lung cancer deaths
and notable gains in life expectancy, since smoking cessation reduces the risk of
developing lung cancer and other tobacco-related conditions.[110] Additionally, integrating smoking cessation interventions, such as telephone-based
counseling with nicotine replacement therapy (NRT), for individuals engaged in LCS
has been estimated to be more cost-effective than LCS alone.[111]
[112]
[113]
As aforementioned, counseling on smoking cessation and interventions is recommended
as part of the SDM visit. Beyond this, no specific guidance is provided on how to
optimally deliver cessation interventions within the LCS process. The Society for
Research on Nicotine and Tobacco and the Association for the Treatment of Tobacco
Use and Dependence mutually recommend that individuals who smoke should be encouraged
to quit at every screening visit and be offered evidence-based smoking cessation interventions,
irrespective of their scan results or motivation to quit. These interventions should
also be offered by SDM or other qualified providers; otherwise, individuals should
be directed to tobacco cessation services.[114] However, many barriers hinder effective implementation of these services, including
a lack of organizational support and limited time and reimbursement allotted to providers
for treatment.[115] Most SDM providers further lack specialized training needed to provide comprehensive
smoking cessation support.[116] Given these constraints, the most effective cessation intervention to implement
in any given LCS program is likely to depend on its population, setting, and institutional
resources and screening workflows.[117]
There is limited but growing evidence on best practices to optimize the delivery of
smoking cessation interventions in LCS programs. In 2016, the U.S. National Cancer
Institute established the Smoking Cessation at Lung Examination (SCALE) Collaboration,
an initiative comprised of eight clinical trials evaluating the efficacy of smoking
cessation interventions in the context of LCS. These trials tested various approaches
ranging from individual therapies to health system interventions, and they collectively
recruited 5,752 participants at 76 clinics.[118] Compared to screen-eligible individuals who smoke in the general U.S. population,
participants enrolled in seven SCALE trials smoked slightly less, but were demographically
similar at baseline.[119] Results from six SCALE trials have been published ([Table 3]).[120]
[121]
[122]
[123]
[124]
[125]
[126]
Table 3
Primary findings of U.S. scale trials
|
Trial
|
Primary findings
|
|
Georgetown Lung Screening, Tobacco, and Health (LSTH) trial[120]
|
In this randomized trial of 818 participants, those who received the intensive (8
telephone counseling sessions with 8 wk of nicotine patch) vs. minimal (3 telephone
counseling sessions with 2 wk of nicotine patch) intervention had a higher self-reported
quit rate at 3 mo (14.3 vs. 7.9%), but not at 6 or 12 mo
|
|
Optimizing Lung Screening Intervention (OaSIS) trial[121]
|
This effectiveness-implementation cluster randomized trial of 26 radiology facilities
across 20 U.S. states found that average tobacco cessation increased from 0% at baseline
to 13% at 6 mo but did not differ by trial group (intervention vs. usual care) at
any measured timepoint (14 d, 3 mo, and 6 mo)
|
|
Program for Lung Cancer Screening and Tobacco Cessation (PLUTO) trial[122]
|
This adaptive sequential, multiple assignment randomized trial enrolling 636 screen-eligible
adults who smoked daily from three large health systems found that adding a prescription
medication therapy management referral to a tobacco longitudinal care (TLC) program
(involving intensive telephone coaching and combination NRT for 1 y with at least
monthly contact) did not improve smoking abstinence at 18 mo among those who did not
respond to early treatment. In addition, the deintensification of TLC to quarterly
contact among those who responded to early treatment had an unfavorable effect on
smoking abstinence
|
|
Personalized Intervention Program: Tobacco Treatment for Patients at Risk for Lung
Cancer (PIP) trial[123]
|
This two-phase, sequential, randomized controlled trial enrolling 188 patients found
no difference in smoking abstinence at 8 wk, comparing standard of care (5 in-person
counseling sessions and 8 wk of nicotine patch) plus gain-framed messaging vs. standard
of care alone. Additionally, participants randomized to receive vs. not receive feedback
on smoking-related biomarkers reported a similar daily number of cigarettes smoked
at 6 mo
|
|
Screen ASSIST (aiding screening support in stopping tobacco) trial[124]
[125]
|
In this randomized 2 × 2 × 2 factorial trial, 642 English- or Spanish-speaking adults
scheduled for lung cancer screening were assigned to 8 groups receiving a multicomponent
intervention with 3 treatment factors: duration of telehealth counseling (4 sessions
over 4 wk vs. 8 sessions over 12 wk), duration of free NRT (2 wk vs. 8 wk), and screening
for social determinants of health and referral to community-based resources (yes vs.
no). At 6 mo, 7-d smoking abstinence was higher for those who received a longer duration
of counseling only; no differences were noted for the other factors. This trial also
found that proactive outreach at multiple points in the screening process is beneficial
for engaging individuals in receiving tobacco treatment
|
|
Project LUNA[126]
|
This trial randomized 630 screening-eligible adults who currently smoke into three
treatment groups: quitline referral for counseling and 12-wk NRT; quitline referral
for counseling plus 12-wk NRT or pharmacotherapy prescribed by the screening clinician;
and integrated care of 12-wk NRT or pharmacotherapy and intensive counseling provided
by dedicated tobacco treatment specialists. Participants who received integrated care
had the highest 7-d smoking abstinence at 3 mo (37.1%), followed by those who received
quitline counseling with medication (27.1%) or without medication (25.2%); however,
the difference in abstinence between those who received integrated care vs. quitline
counseling with medication decreased at 6 mo (32.4 vs. 27.6%)
|
While not all SCALE trials identified group differences for their primary outcomes,
they demonstrated the feasibility of integrating various smoking cessation interventions
into LCS in different settings, as well as the importance of providing longitudinal
behavioral and medication support for cessation. In the UK QuILT trial that randomized
412 adults aged 55 to 75 attending a targeted lung health check, those who received
immediate support from a trained smoking cessation counselor with pharmacotherapy
versus usual care (brief advice for quitting and signposting to cessation services)
had higher 3-month quit rates (29.2% vs. 11%).[127] A meta-analysis of 10 RCTs of smoking cessation interventions delivered with LCS
(including LSTH and QuILT) suggests that more intensive interventions are the most
effective relative to usual care.[128] Unequivocally, continued efforts are vital to reducing barriers to smoking cessation
and implementing evidence-based strategies that support individuals to quit smoking.
Lung Cancer Screening Uptake
Despite strong evidence that annual LCS with LDCT reduces mortality and recommendations
endorsing LCS from multiple organizations, LCS uptake remains low in the United States,
with 16.4% (95% CI: 15.6–17.2) of the 13.5 million eligible individuals screened in
2022,[31] the last year for which national data are available. Across the United States, LCS
rates have ranged from 8.6 to 28.7%, with Northeastern and mid-Atlantic states tending
to have higher rates. Currently, national self-reported LCS rates are available from
the Centers for Disease Control and Prevention's Behavioral Risk Factor Surveillance
System (BRFSS) through an LCS module that was optional until 2022. In 2022, the BRFSS
LCS question asked if the respondent had any CT scans of the chest to check or screen
for lung cancer.[129] No studies have validated the BRFSS LCS survey question, and it is possible that
responders answer yes to include both screening and diagnostic chest CTs or that they
may not recall accurately, both of which would result in overestimation of LCS uptake.
The National Health Interview Survey[130] and the Health Information Trends Survey[131] also have cancer control supplemental modules and, in some years, asked about LCS.
While administrative claims data are also used to derive estimates of LCS uptake,
these data do not contain sufficient detail to ascertain P-Y or YSQ and are limited
to individuals with health insurance.[132] Electronic health records have also been used to assess LCS uptake and tend to have
more, but not necessarily sufficient details on smoking information, such as P-Y and
YSQ.
Several factors are associated with increased LCS uptake. A meta-analysis examining
predictors of LCS in the United States found that Black or Hispanic adults had lower
rates of LCS than White adults.[133] It also found geographic differences with higher rates in the Northeast and differences
by socioeconomic status. The presence of comorbid conditions, particularly COPD, was
also associated with higher rates of LCS uptake.
Interventions to increase LCS uptake have focused on (1) improving the identification
of eligible individuals; (2) education to the community and providers; and (3) navigation
to services.[134] A recent review noted that most LCS interventions address SDM and initial LCS uptake
rather than LCS eligibility assessment, annual adherence, or diagnostic follow-up
of screen-detected findings.[135]
Lung CT Screening Reporting and Data System
To facilitate standardized reporting and management of findings from LDCT screening
exams, the ACR first released the Lung CT Screening Reporting and Data System (Lung-RADS)
in 2014 (v1.0), with an update to v1.1 in 2019 and an update to Lung-RADS v2022 in
November 2022.[136] The most recent updates include new classification criteria of atypical pulmonary
cysts, juxtapleural nodules, airway-centered nodules, and inflammatory or infectious
findings. Additionally, the latest Lung-RADS version provides clarification around
volumetrics, nodule growth, the “S” modifier, and stepped management of nodules that
are stable or decreasing in size. Lung-RADS continues to evolve over time based on
new data and clinical insights.
Annual Adherence
For LCS to be effective in reducing mortality, adherence to recommended screening
intervals is needed. Among individuals with a negative or normal LCS exam, the Lung-RADS
recommendation is to return for screening annually. Measuring annual adherence across
studies is challenging due to differences in definitions around the timing of follow-up
and a need for standardization.[137]
Numerous studies have evaluated annual adherence to LCS.[73]
[74]
[138]
[139]
[140]
[141]
[142]
[143]
[144]
[145] A meta-analysis by Lopez-Olivo et al reported a pooled LCS adherence rate of 55%
(95% CI: 44–66), with adherence rates across studies ranging from 12 to 91%.[143] The wide variability in rates is likely due to differences in definitions, study
populations, and study settings. Results of the pooled analyses showed factors associated
with higher rates of annual adherence include centralized versus decentralized screening
programs, having formerly smoked versus currently smoking, White versus other races,
and completing 4 years or more of college versus not. A recent multicenter study of
10,170 individuals screened for lung cancer found that adherence to annual LCS was
associated with increased lung cancer detection, especially at earlier stages; however,
adherence declined annually following baseline screening, further signifying the need
to improve adherence.[140]
Screen-Detected Findings and Management
Effective follow-up and management of pulmonary nodules detected from LCS is paramount
to realizing the reported net benefits of LCS observed in the RCTs. Lung-RADS recommends
specific testing and time intervals for follow-up depending on pulmonary nodule size,
attenuation, shape, margin, calcification, and growth rate. Retrospective application
of Lung-RADS criteria to the NLST resulted in 13.7% of baseline exams and 5.8% of
subsequent exams classified as positive and warranting additional follow-up.[146] In real-world settings, approximately 11.4 to 19.6% of LCS exams are classified
as positive (Lung-RADS 3, 4A, 4B, or 4X).[147]
[148]
[149]
[150]
[151]
[152] In a multi-center cohort study, absolute rates of downstream imaging and invasive
procedures were 31.9 and 2.8%, respectively.[152]
Limited data indicate suboptimal adherence to recommended follow-up care following
positive LCS findings. In a prospective U.S. cohort study, overall adherence to recommended
follow-up care was 42.6%, with an increasing trend in adherence from Lung-RADS category
3 to 4B/4X (30–68%), and factors related to poorer adherence included Black race,
male sex, and current smoking status.[153] Another study similarly noted that almost half of the patients had delayed follow-up
care after positive findings (i.e., >30 days beyond recommended Lung-RADS intervals),
and among those diagnosed with lung cancer, delayed follow-up care was associated
with clinical upstaging.[154]
Studies have documented higher rates of malignancy with increasing Lung-RADS category.
In one study, malignancy rates corresponding to Lung-RADS categories 3, 4A, 4B, and
4X were 3.9, 15.5, 36.6, and 76.8%, respectively.[155] Lung cancer detection rates by LDCT LCS have ranged from 0.56 to 4.5%.[156]
[157]
[158]
[159]
Incidental Findings and Management
Incidental findings (IFs) detected on LDCT LCS are defined as imaging abnormalities
unrelated to lung cancer and are both pulmonary and extrapulmonary in nature. While
some IFs may be benign, other IFs may be clinically significant (e.g., significant
incidental findings [SIF]) and require subsequent follow-up, including diagnostic
work-up and management. In 2023, the ACR released a quick reference guide for IF detected
on LCS, which gives an overview of the most common IFs.[160]
Among the LDCT screening arm of the NLST, 18% of exams had at least one SIF, with
the most common types being pulmonary findings (43%), coronary artery calcification
(CAC; 12%), and masses or suspicious lesions (7%).[161] SIF were reported for about 8% of participants in the NELSON and COSMOS trials and
for about 10% of those in the Australian and Canadian ILST.[162]
[163]
[164] Similar to the NLST, the most frequent IFs were CAC and emphysema.
There is limited research on IF detected on LCS outside of RCTs.[165] In real-world U.S. settings, Lung-RADS specifies using an “S” modifier to indicate
a clinically or potentially clinically significant IF that is unrelated to pulmonary
nodules. However, prior studies have shown that the “S” modifier does not capture
all IF for which clinical follow-up is recommended. Hence, studies estimating SIF
prevalence have applied differing definitions and have reported wide variation ranging
from 16 to 69%.[166]
[167]
[168]
[169]
[170]
[171] A scoping review of 32 articles examining CAC detected from LCS found CAC prevalence
of 14.8 to 98%.[172]
The net benefits of detecting SIF on LDCT LCS are unknown. While detecting clinically
actionable findings has been shown to favorably impact outcomes, there is also the
potential to detect nonsignificant IF that may cause unneeded anxiety, unnecessary
imaging or invasive procedures, or financial distress. This poses challenges for patients,
providers, systems, and payors. Additional research to evaluate the clinical benefits
and harms of SIF detected on LCS is needed.
Disparities
Established drivers of LCS disparities include healthcare access and costs.[173] Accessibility to LCS intrinsically depends on travel distance to LDCT facilities,
with distance being inversely associated with population density and urbanization.[174]
[175] Geospatial analyses estimate that 5% of the eligible U.S. population has no access
to any LDCT facility within 40 miles, and that lack of access is especially pronounced
in rural and socioeconomically disadvantaged areas and populations.[175]
[176]
[177]
[178]
[179]
[180]
LCS utilization is further influenced by health insurance access and coverage. Analyses
using the BRFSS survey data have found a greater proportion of screened non-Hispanic
Black respondents were of Medicare age, despite similar LCS rates between non-Hispanic
White and Black respondents,[181] and that gaining access to Medicare coverage increased LCS in screening-eligible
men.[182] Additionally, U.S. claims data suggest that individuals with higher total out-of-pocket
medical costs are less likely to adhere to annual LCS.[183]
To date, the few interventions addressing social determinants of health in LCS have
favorably resulted in increased screening rates, as shown for other screening-associated
cancers.[184] Various proposed opportunities to mitigate disparities include increasing public
awareness about LCS, addressing misconceptions and stigma associated with lung cancer,
establishing mobile LCS clinics in underserved communities, and fostering partnerships
for community engagement.[185]
[186]
Personalized Screening and New Technologies: Emerging Data and Considerations
Applying personalized approaches holds great promise for enhancing the effectiveness,
efficiency, and accessibility of LCS. A growing body of research focuses on integrating
risk prediction modeling, biomarkers, and artificial intelligence (AI) into LCS. Although
emerging data are encouraging, including that primary care clinicians are open to
adopting personalized LCS,[187] most proposed innovations require more robust evaluation and consideration before
widespread clinical implementation.
Risk Prediction Models
The application of lung cancer risk prediction models has been largely focused on
tailoring the selection of high-risk adults who have smoked for LCS. A major consideration
is the optimal risk threshold upon which to screen. This choice should strike the
best balance between individual benefits and harms along with program efficiency,
costs, and impact.[188] Although adopted, the PLCOM2012 6-year risk threshold of ≥1.51% was not derived considering cost-effectiveness.[189] Optimal risk thresholds must be set for each model, as different models generate
varying absolute risk estimates for the same individual.[190] Risk thresholds must also be reassessed and adjusted as population characteristics
change over time.[57]
Evidence increasingly supports using the PLCOM2012 and LLPV2 models in targeted LCS programs.[191] However, the clinical feasibility and acceptability of newer models, especially
ones designed to incorporate comorbidities, life expectancy, and/or individual preferences,
remain largely untested.[59] Accurate collection of required input data is critical for effective implementation
of model-based risk assessment. Given the time constraints clinicians face, embedding
automated risk calculation within electronic health records may help to streamline
workflows and promote wider adoption of personalized LCS. Additionally, developing
best practices to prevent unnecessary screening of low-risk populations is needed.
Validated risk prediction models can perform differently when applied to different
populations and settings. Models that perform well in predicting lung cancer risk
of ever-smoking adults in Western populations have been found to perform suboptimally
when applied to ever-smoking adults in Asian populations.[192] Also in Asia, approximately 30 to 40% of all lung cancers arise in adults who have
never smoked, a higher proportion than observed in the United States and Europe, highlighting
the need to consider factors beyond age and smoking history in assessing risk.[193] While extending models to identify high-risk adults who have never smoked may be
beneficial in broadening the reach of LCS, more definitive evidence is required to
support tailored screening of never-smoking adults across diverse populations.
Biomarkers
Biomarkers can facilitate early detection of lung cancer by indicating the presence
of associated molecular alterations before clinical symptoms manifest. Various lung
cancer biomarkers are under investigation for their use with LDCT to refine the selection
of individuals for LCS or improve risk stratification after lung nodule detection,
as well as their standalone use to screen for lung and other cancers concurrently.
Blood-based biomarkers are the furthest along in clinical development, although relatively
few have moved beyond early evaluation.
Autoantibodies
In early studies, the EarlyCDT-Lung test, an assay profiling seven tumor-associated
autoantibodies,[194] demonstrated high specificity (91%) and low sensitivity (34–37%), with better performance
for early-stage lung cancer, and its ability to differentiate malignant from benign
pulmonary nodules.[195]
[196]
[197]
[198] The Early Diagnosis of Lung Cancer Scotland trial randomized over 12,000 high-risk
participants to receive the EarlyCDT-Lung test or usual care, and test-positive participants
received LDCT every 6 months up to 2 years. More early-stage lung cancers were diagnosed
in the intervention than the control arm, with no difference in mortality after 2
years[199]; however, 5-year mortality was lower in those tested (vs. untested) for autoantibodies
and diagnosed with lung cancer within 2 years.[200] As designed, the trial could not assess the added value of the EarlyCDT-Lung test
to LDCT, only its benefit to select individuals for LDCT screening.
Proteins
Nodify XL2 is a plasma-based test to identify likely benign lung nodules, integrating
measurement of two proteins (LG3BP and C163A) with five clinical factors (age, smoking
status, nodule diameter, nodule edge characteristics, and nodule location). It was
validated in the PANOPTIC trial for 8 to 30 mm lung nodules with a pretest probability
of cancer of ≤50%, achieving 97% sensitivity, 44% specificity, and 98% negative predictive
value.[201] Its clinical utility in managing new solid lung nodules of low to moderate cancer
risk is presently under evaluation in a multisite randomized trial (NCT04171492).
This test is commercially available and covered by Medicare for certain patients with
lung nodules. Additionally, a four-marker protein panel (4MP; CEA, Cyfra21-1, CA125,
and Pro-SFTBP) combined with smoking history has shown greater sensitivity (63%) compared
to smoking history alone (43%) in selecting individuals for LCS.[202] The 4MP in combination with the PLCOM2012 model has further demonstrated improved risk assessment for LCS, relative to the
2021 USPSTF LCS eligibility criteria.[203]
MicroRNAs
A plasma-based 24-miRNA signature classifier and a serum-based 13-miRNA signature
test have demonstrated the potential to reduce LDCT false-positive rates with high
sensitivity (78–87%) and specificity (75–81%).[204]
[205]
[206] In the BioMILD trial of over 4,000 heavy-smoking individuals, the 24-miRNA signature
classifier was used conjunctively with baseline LDCT to personalize LCS intervals,
showing that individuals classified as positive on both LDCT and miRNA signature had
a higher 4-year lung cancer incidence and 5-year lung cancer mortality.[206] The COSMOS II study is prospectively examining the 13-miRNA signature test alongside
LDCT in approximately 10,000 high-risk individuals.[207] Other miRNA panels have been examined in selecting individuals for LCS[208] and assessing the risk of solitary pulmonary nodules.[209]
Circulating DNA
Cell-free DNA (cfDNA) analysis is a major focus of investigation in multicancer and
LCS. The commercially available Galleri test, which analyzes cfDNA methylation patterns,
initially exhibited 55% sensitivity and 99% specificity for detecting >50 cancer types
across all stages, with about 20% sensitivity for early-stage lung cancer.[210] This test is currently being validated for detecting multiple cancers at an early
stage in over 13,000 UK SUMMIT participants at high-risk for lung cancer (NCT03934866).
Its safety and performance are also under evaluation in PATHFINDER 2, a prospective
interventional study comprising 35,000 U.S. adults eligible for cancer screening (NCT05155605).
Based on analyses from the Copenhagen City Heart Study, DNA methylation could also
be used with existing screening criteria to enhance the selection of individuals for
LCS by excluding those at the lowest risk.[211] DELPHI (DNA evaluation of fragments for early interception) analyzes genomewide
cfDNA fragmentation profiles to detect cancer.[212] The CASCADE-LUNG study is underway to prospectively validate DELPHI test performance
in detecting lung cancer among nearly 12,000 screening-eligible adults (NCT04825834).
The FIRSTLUNG cluster randomized trial is further assessing the clinical utility of
DELFI on promoting LCS uptake in primary care settings (NCT0614570).
Beyond blood, other promising sources of biomarkers include airway epithelia, exhaled
breath, sputum, and urine. Yet, some constraints hinder the utility and application
of biomarkers in LCS.[213]
[214] Blood and sputum tests have been generally limited by low sensitivity, especially
for detecting small tumors. Assessing airway epithelia via bronchoscopic brushing
is invasive. Methods for sampling and analyzing volatile organic compounds in exhaled
breath lack standardization. Urine biomarkers can be influenced by diet, medication,
and comorbidities. Most notably, many biomarkers have yet to undergo rigorous prospective
validation for their intended use in LCS.
AI
With LCS implementation, radiologists face greater demands to interpret higher volumes
of CT images promptly and accurately. AI models developed for pulmonary nodule detection
and classification show promise in overcoming this challenge through automating image
analysis and reducing inter-reader variation. Compared to radiologists, AI models
for nodule detection have exhibited higher sensitivity (86–98% vs. 68–76%) but lower
specificity (78–87% vs. 87–92%), and those for classification of nodule malignancy
have generally exhibited better sensitivity (61–93% vs. 77–88%), specificity (64–96%
vs. 62–84%), and accuracy (65–92% vs. 73–86%).[215] Evaluating LDCT interpretation times and outcomes across simulated AI use case scenarios,
using AI as a prescreener (i.e., radiologists only interpret exams with a positive
AI result) was the only scenario that led to a lower recall rate (20.8% vs. 22.1%),
lower mean interpretation time (143 seconds vs. 164 seconds), and higher per-exam
specificity (90.3% vs. 88.8%), relative to radiologist interpretation without AI.[216] Other scenarios included using AI as an assistant (i.e., radiologists interpret
all exams with AI assistance) and using AI as a backup (i.e., radiologists reinterpret
exams when AI indicates a missed finding). Data from the 4-IN-THE-LUNG-RUN and UK
LCS trials further suggest that using commercial AI software as a first read to independently
rule out negative LDCT scans at baseline can outperform radiologists and reduce their
workload, without considerably missing diagnostic referrals or lung cancers.[217]
[218]
AI models that predict future lung cancer risk have primarily emerged since 2020,
exhibiting better performance than traditional regression-based models.[219] While most traditional risk prediction models consider epidemiologic and clinical
factors, several AI models consider imaging data only. Deep learning models incorporating
imaging data from LDCT scans, such as the Ardila et al[220] and Sybil[221] models, have especially shown strong predictive performance (pooled area under the
curve: 0.85; 95% CI: 0.82–0.88), offering the potential to tailor screening frequency
to an individual's predicted lung cancer risk from baseline or subsequent LDCT scans.[219] Notably, Sybil predicts risk from a single LDCT scan without additional clinical
data or radiologist annotations, has been externally validated in several populations,
and is publicly accessible.[221] AI can further support opportunistic CT screening for other chronic conditions,
including cardiovascular disease, emphysema, and osteopenia, as an added benefit toward
improving population health.[222]
To advance integration of AI-based tools in LCS, large-scale prospective validation
of their performance and clinical utility is especially needed in diverse populations.
That encompasses examining how imaging parameters and reconstruction techniques influence
their performance, given variability in the imaging scanners and protocols used across
clinical settings, as well as evaluating how AI-based tools impact the performance
of radiologists. Investigating the interpretability of results from deep learning
models through correlation with input data is also important to better understand
how predictions are made.[223] Although relatively in its infancy, AI shows immense potential to transform LCS,
particularly in facilitating clinical decision-making.