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What is the appropriate interval between endoscopies for the early detection of gastric cancer?Referring to Li WQ et al. p. 848–858
In this issue of Endoscopy, Li et al. describe a population-based, 8-year, prospective study examining the effect of endoscopic gastric cancer screening on the detection of gastric cancer and the reduction of gastric cancer mortality . The study included 375 800 residents of Linqu, a district in northeastern China that has among the highest mortality rates for gastric cancer in the world. The study also examined the optimal screening interval for repeated endoscopy. The results showed that endoscopic screening reduced the frequency of detection of gastric cancer and significantly reduced mortality from gastric cancer. It was concluded that the interval between endoscopic examinations should be no more than 2 years, and especially no more than 1 year, depending on the degree of precancerous lesions in the gastric mucosa and the presence of intestinal metaplasia or intraepithelial neoplasia.
First and foremost, the two endoscopists who performed the gastroscopic examinations should be congratulated for their hard work and enthusiasm, searching for lesions in 14 670 patients with five fixed-point gastric biopsies. It would be interesting to know how long it took them to perform a single endoscopy. We know that endoscopy of the upper gastrointestinal tract is an effective method for the early diagnosis of esophageal and gastric cancer, but there are few reports that scientifically prove its efficacy, owing to cost and lack of staffing resources.
“To improve the efficiency of screening for gastric cancer, it is necessary to narrow down the target population for screening. The diagnosis of Helicobacter pylori infection is indispensable for this purpose.”
In Japan, where the incidence and mortality rates of gastric cancer are high, mass screening using gastric X-ray examination has traditionally been carried out. With the spread of endoscopy, studies have shown that endoscopy is superior to gastric X-ray examination in the early detection of gastric cancer, but the evidence of endoscopy in reducing gastric cancer mortality had not been clear, so it had not been widely used. Recently, a study conducted by Hamashima et al. to investigate whether endoscopy is an effective screening method reported a 67 % reduction in gastric cancer mortality in the Tottori area after 6 years of observation, compared with a group that received gastric X-ray examination . Although it is known that endoscopic screening is an effective method of detecting gastric cancer and reducing mortality, there are several problems with endoscopic screening in Japan. The main problem is a severe shortage of endoscopists. Gastric X-ray examination can be performed by a radiology technician, and a large number of cases can be examined in a short time with gastric X-ray examination. Furthermore, a mobile screening vehicle equipped with fluoroscopy equipment can travel to different areas to perform the examination. Therefore, endoscopy has not been widely used for gastric cancer screening of rural populations. In 2018, the Guideline for Health Education and Screening for Cancer Prevention was revised to allow endoscopic screening in addition to gastric X-ray examination . The guideline also mentions the role of Helicobacter pylori eradication in the prevention of gastric cancer, and the importance of close cooperation with gastric cancer screening when implementing health education programs for gastric cancer prevention.
In the clinical study by Li et al., the detection rate of gastric cancer at the first endoscopy was 0.177 % (19/10 736), and a further 30 cases were detected during subsequent repeat endoscopies. In contrast, 2699 cases of gastric cancer were diagnosed over an 8-year period in residents who did not undergo endoscopic screening, of whom 1615 (59.8 %) died of gastric cancer. Of the 30 cases detected by repeated screening, 24 were detected by repeated screening and 6 were reported in cancer registries or autopsy reports. Only one case, initially diagnosed as high grade intraepithelial neoplasia, was described as progressing to invasive gastric cancer during follow-up; however, it would be useful to know how the 24 cases detected during follow-up progressed, and whether any cases were missed. In particular, three patients who had undergone repeated endoscopic examinations died of gastric cancer. The rate of growth of gastric cancer varies greatly according to the gross morphology (i. e. raised or depressed) and histology. In a previous study by my group, the tumor doubling time of gastric cancer was 10.1 months on gastric X-ray examination . In general, the growth of early gastric cancer is slow  , but some gastric cancers, such as scirrhous type gastric cancer, progress more rapidly and have a poorer prognosis . It would be interesting to know the morphology and histology of the gastric cancer in the three patients who died in the current study.
To improve the efficiency of screening for gastric cancer, it is necessary to narrow down the target population for screening. The diagnosis of H. pylori infection is indispensable for this purpose. Endoscopic findings can be used to diagnose H. pylori infection , and gastric biopsy can be used to evaluate H. pylori infection. Furthermore, if gastric biopsy tissue is collected, the risk can be assessed by OLGA  or OLGIM . We would encourage the consideration of these items in any future subanalyses. Furthermore, it is clear that eradication of H. pylori can prevent the development of gastric cancer in areas where gastric cancer is common , and this should be a subject for further clinical research.
Article published online:
11 April 2022
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