Review for 10.1186/s12876-020-01517-3 (2020)

Reviewer’s report
Title: 
Initial results from a multi-center population-based cluster randomized trial of esophageal and
gastric cancer screening in China
Version: 
0 
Date: 
13 Jul 2020
Reviewer's report:
This study investigated the efficacy of upper endoscopic screening in reducing mortality of esophageal
cancer and gastric cancer in high-risk areas and in non-high-risk areas of China. Three high-risk areas and
four non-high-risk areas were selected as screening centers. Clusters (villages/communities) were
randomly assigned into the intervention group or control group. In the intervention group, participants
from high-risk areas were automatically invited to receive upper endoscopy. Participants from non-high-
risk areas, only subjects who were identified as high-risk individuals using a questionnaire were invited to
receive endoscopy. The detection rates and early detection rates of esophageal cancer and gastric cancer
were evaluated. The detection rates was of both esophagus and stomach were higher in high-risk areas than
in non-high-risk areas, even though only high-risk individuals were screened in non-high-risk areas.
There are several points to be addressed.
1. Three high-risk areas were defined by higher mortality rate based on National survey. The higher
detection rate in high-risk areas is a matter of course.
2. Comparing participants automatically identified as high-risk individuals in high-risk areas and
participants identified as high-risk individuals using the questionnaire in non-high-risk areas is not
accurate. The effectiveness of screening endoscopy for non-high-risk individuals in high-risk areas
identified using the questionnaire should be shown.
3. The early-detection rate was lower in non-high-risk areas than in high-risk areas. This means that the
questionnaire was not effective for identifying high-risk individuals in non-high-risk areas. The
questionnaire was not found in the reference 10. The questionnaire should be shown as a supplement. 
4. Contrary, detection rates of non-early-stage esophageal cancer were 17/26633 (0.0006) in high-risk
areas and 7/11289 (0.0006) in non-high-risk areas. Detection rates of non-early-stage gastric cancer were
70/26633 (0.0017) in high-risk areas and 24/11289 (0.0021) in non-high-risk areas. Detection rates of
non-early-stage cancer were not so different. These results were quite interesting but not discussed in the
manuscript.
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