Gastric cancer detected by mass survey. Comparison between mass survey and outpatient detection.

Although the incidence of stomach cancer in Japan has decreased only slightly, the mortality has decreased markedly. The main reason for this success is the early diagnosis of cancer, to which mass survey has contributed. From 1964 to 1985, 290,914 screening examinations were done at the Mass Survey Center of the Cancer Institute Hospital, Tokyo. In 474 people (0.16%) cancer was detected, and of those, 52% were in an early stage of disease. For the mass survey group, the 5-year survival rate was 80%, and the 10-year survival rate 78.5%. The outpatient group rates were 56.2% and 55.1% for 5 and 10 years, respectively. This difference could be explained by the higher percentage of early gastric cancer and less extensive lymph node metastasis in patients with serosal involvement, in the outpatient group. The 10-year survival results show that early treatment results in an absolute better long-term survival. This refutes the hypothesis that 5-year survival rates of early gastric cancer patients are biased because of lead time of early diagnosis. Mass survey, even for a small district, provides an excellent opportunity to detect gastric cancer in people without symptoms. The high percentage of cases detected with cancer in an early stage reduces stomach cancer mortality.