Mobile lung cancer screening in resource-limited regions: brock model assessment as a marker of malignancy predictability in intermediate- and high-risk (lungRADS 3 and 4) participants of the Brazilian early lung cancer screening trial (BRELT3)

Keywords

brock - lung cancer screening - low-dose computed tomography - LungRADS

Introduction: BRELT 1 (2016) and BRELT 2 (2022) studies demonstrated the feasibility of lung cancer screening (LCS) with low dose computed tomography (LDCT) in Brazil. BRELT3 is conducted with a mobile LCS unit. The Brock malignancy probability pre-test (PMB) uses clinical factors (age, sex, family history) and radiological factors (emphysema, nodule size and location, nodule type and count, spiculation) to predict cancer risk has been applied in various LCS. The use of PMB at regional LCS programs has not yet been described.

Objectives: To evaluate the PMB findings and biopsy recommendations in intermediate and high risk LungRADS (LR 3 and 4) subjects of BRELT3.

Method: This prospective cohort trial included subjects aged 50-80 years, current or former smokers (cessation time ≤ 15 years) with ≥ 20 pack-years and LDCT classified as LR 3 or 4. Clinical and image data were analyzed. The PMB with a 10% threshold (British Thoracic Society 2015) was applied. Student's t-tests or Mann-Whitney tests were used for continuous variables, and chi-square or Fisher's exact tests for categorical variables. This trial was approved by the Ethics Committees of SENAI-CIMATEC and Santa Izabel Hospital (CAAE: 67431523.6.0000.9287/ 67431523.6.3001.5520).

Results: A total of 1,306 LDCT were performed between August 2023 and May 2024 and 129 (9.9%) had positive screening findings, of which 41.1% were classified as LR3 and 58.9% as LR4. The median age was 64 years, and most participants were black (85%), current smokers (66%), with negative family history of lung cancer (75%) and had evidence of emphysema on LDCT (52%). Most nodules were single (79.8%) and solid (79.1%), with an overall mean size of 12 mm, where 11,54% had PMB > 10%. LR3 nodules were smaller (8.65 vs 14.27 mm) and had lower PMB (6.44 x 15.1%). Twenty biopsies were indicated by a multidisciplinary board (15.5%). So far, 4 (four) were positive for lung cancer. Biopsy indications were more frequent in larger nodules (21.70 x 11.62 mm) and with higher PMB (22.96 x 12.30%). Critical factors for biopsy were LR 4B/4X vs. 4A (OR 12.47; 95% CI: 3.492 - 44.51; p < 0.05) and PMB > 10% (OR 4.67; 95% CI: 1.704 - 12.813; p < 0.05).

Conclusions: Our study shows that PMB can help to discriminate nodules eligible for biopsy. Nodule size, LR 4B/4X classification, and PMB scores > 10% were key factors in the decision-making process. The PMB may be considered at LCS programs to help decision making regarding biopsy.

Corresponding author: Audrey Cabral Ferreira de Oliveira (e-mail: [e-mail]).

 

MissingLinkText

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
06 May 2025