10.1055/a-1478-3281Gastric cancer is the fifth most common cancer worldwide and the third leading cause
of cancer-related death in the world [1]
[2]. Given the high incidence of gastric cancer in Asia, rigorous screening strategies
have been implemented over the years, resulting in enhanced detection at an early
stage. This shift in the timing of diagnosis is critical for prognosis, as early gastric
cancers (EGCs) have negligible risk for lymph node metastasis (LNM) [3]
[4]. Importantly, endoscopic resection can be curative for select EGCs that meet curative
resection criteria, as established by the Japanese Gastric Cancer Association (JGCA)
[5]. When compared to surgery, endoscopic resection for EGCs in Asia is associated with
similar oncological outcomes, yet it is a less invasive stomach-preserving technique
with improved quality of life [6]. Hence, ESD has become the standard of care for EGCs in Asia, with an increasing
interest in the West over recent years.
In this issue of Endoscopy International Open, Barakat et al retrospectively analyzed
the rates of endoscopic and surgical resection in the United States for EGCs that
meet the JGCA absolute and expanded curative resection criteria [7]. The authors used data on gastric cancers collected from the Surveillance, Epidemiology
and End Results (SEER) database from 2010 to 2015. During this period, 161,854 gastric
cancers were identified, of which 2219 were EGCs (1074 T1a and 1145 T1b lesions).
Data on the type of resection were available for 1733 of these EGCs. Overall, 304
lesions (17.5 %) were treated endoscopically while 1430 (82.5 %) were surgically resected
(P = 0.0001). The proportion of EGCs resected endoscopically versus surgically was higher
if they met the JGCA absolute criterion (T1a, well-differentiated, < 2 cm) (26 %),
as compared to other expanded criteria (9 %–14 %). Temporal analysis from 2010 to
2015 showed a near 3-fold increase in endoscopic resection for EGCs and a concomitant
and proportional downtrend in surgery. Lastly, the authors reported comparable survival
rates between the two treatment modalities based on Kaplan-Meier analysis.
Barakat et al. should be congratulated for performing a large US population-based
study evaluating resection trends for EGCs. Overall, the authors show that surgery
remains overwhelmingly the predominant practice for the management of EGCs in the
United States, albeit the rate of endoscopic resection has slowly increased. Gastric
cancer is one of the leading causes of cancer-related morbidity and mortality. Given
its notoriously low survival rates, early detection and resection is the most effective
strategy to improve prognosis. Yet, as demonstrated by this study, of the 161,854
gastric cancers identified in the SEER database from 2010 to 2015, only a dismally
low 2219 (1.37 %) were EGCs, further highlighting that most gastric cancers in the
United States are diagnosed in late stages. This is in stark contrast to Asia, where
systematic gastric cancer screening efforts have increased rates of early detection
and improved survival. It should be noted that the estimated number of new cases of
gastric cancer per year in the United States, including 2021, is higher than the number
of new cases of esophageal cancer [8]. Yet, there are no guidelines for gastric cancer screening as opposed to those established
for Barrett’s esophagus and esophageal cancer. While mass gastric cancer screening
may not be cost-effective in the United States implementation of targeted screening
of high-risk populations (i. e. immigrants from high-incidence region, family history
of gastric cancer) may increase the detection of EGCs suitable for endoscopic resection
without the need for surgery [9]. We should emphasize that systematic and detailed examination of the stomach is
a prerequisite for endoscopy to be an effective tool for gastric cancer screening.
The lack of defined quality metrics for upper endoscopy in the United States is associated
with variability in clinical practice and presumably the notoriously high rates of
missed gastric cancers at endoscopy reported in the West [10]. Increasing awareness of gastric cancer, establishing a structured training system
for endoscopists and quality assurance for endoscopy are essential for more successful
detection of EGCs [11]
[12]
[13].
According to this study, most of the EGCs in the SEER database were managed surgically
as opposed to endoscopic resection (82.5 % versus 17.5 %; P = 0.0001). Several potential explanations may account for these findings. For one,
the limitations of endoscopic mucosal resection (EMR) for the management of EGCs are
well recognized. When compared to ESD, EMR is associated with a very high rate of
incomplete resection, even for EGCs < 20 mm [6]. Hence, ESD has long replaced EMR as the standard method in Asia, accounting for
over 90 % of endoscopic resections for EGCs in Japan [4]. Secondly, the study captured data from 2010 to 2015, a period in which the US ESD
experience was limited. In fact, a survey analysis by our group around this time confirmed
that most US endoscopists training in ESD had yet to incorporate this technique into
their clinical practice [14]. Nonetheless, with the increasing availability of dedicated ESD devices, accessories,
and structured training courses, we have witnessed increasing adoption of this technique
in recent years, as suggested by the upward trend in endoscopic resection for EGCs
reported in this study. Furthermore, it is worth noting that some studies from the
West have suggested a higher rate of LNM in EGCs as compared to data originating from
Asia, leading to the speculation of differences in biological aggressiveness of EGCs
in the West [15]. Nonetheless, the discrepantly higher rate of LNM reported in the West as compared
to Asia appears to be primarily driven by lesions meeting the expanded criteria, whereas
EGCs within the absolute criteria have been associated with excellent outcomes and
negligible risk for LNM [16]
[17]. Hence, not surprisingly, most of the endoscopic resections for EGCs reported in
this study were for lesions meeting the absolute criteria; albeit it remains unclear
how precise histopathological staging was obtained from the SEER database, particularly
for the non-surgical specimens. Noteworthy, histological evaluation of endoscopic
and surgically resected specimens in Japan is routinely performed in a far more systematic
and detailed manner when compared with specimen handling in the West [15]
[18]. As the practice of ESD continues to grow in the United States, we need to embrace
the same meticulous approach to lesion characterization and histological staging from
our Asian counterparts to ensure best practices and avoid misclassification of more
advanced disease and risk for LNM.
The study by Barakat et al points towards the current reality in the United States:
surgery remains overutilized for the treatment of EGCs. Nonetheless, caution should
be exercised when interpreting these findings, given the well-recognized limitations
of a population-based study utilizing the SEER database, including: missing data (i. e.
data on resection type was only available in a subset of patients with EGCs), coding
reliability (i. e. histopathology), and selection bias when evaluating long-term outcomes
after cancer-directed therapy. Yet, it is clear that efforts to increase the detection
of EGCs must be an ongoing point of emphasis. Equally as important, we need to raise
awareness of endoscopic resection, specifically ESD, as the primary modality for most
EGCs. At this point, multiple studies from the West have corroborated the feasibility
and safety of ESD for the treatment of dysplastic lesions and EGCs when performed
at centers with the appropriate expertise [16]
[17]
[19]. Our ultimate goal should be to provide patients with appropriate stage-specific
therapy based on well-established criteria. Barakat and colleagues suggests that endoscopic
therapy for EGC in the United States may be trending in the right direction, albeit
the gap with surgery is still wide and much work remains to be done.
