Detection and treatment of early cancer in high-risk populations.

In this paper we describe how to more efficiently detect and treat early gastric cancer (EGC) in high-risk populations. For detection, we first assess the value of known risk factors from the viewpoint of availability for cancer screening. Serum pepsinogen appears to be the most useful and realistic of the factors examined, although its adequacy needs to be assessed in high-risk populations other than those in Japan. Helicobacter pylori infection is known to be a universal risk factor (or gastric carcinogen), and several interventional studies have recently shown positive results. However, H. pylori infection can be eradicated from at-risk populations, thereby decreasing its availability for cancer screening. Smokers are thought to be at risk epidemiologically, but the efficacy of screening in this population has yet to be elucidated, and further studies are warranted. Gender and aging can be risk factors in Japanese populations; male gender and old age are predominant in the intestinal type of carcinoma which is dominant in Japan, although this is not the case in the West. As for early diagnosis of cancer, only endoscopy can be commonly used for the detection of gastritis-like EGC, seen as a faint mucosal irregularity or discoloration. To make early diagnosis more accurate, it is indispensable to carry out detailed endoscopy together with careful scrutiny of the mucosa using dye-spraying techniques. The remarkable progress of early diagnosis in Japan prompted the endoscopic treatment for less invasive EGCs. The first success was with endoscopic mucosal resection (EMR). Although convenient, its therapeutic efficacy is inadequate, particularly for larger lesions. Endoscopic submucosal dissection (ESD) has no limitation on resection size and is expected to replace surgery, although it needs a high level of skill and there are several technical problems to be solved.