Overview of colorectal cancer in Japan: report from the Registry of the Japanese Society for Cancer of the Colon and Rectum.

BACKGROUND AND PURPOSE: In Japan, the incidence of colorectal cancer has increased remarkably since World War II, and interest in this cancer has grown rapidly among Japanese clinicians and pathologists. As a result, the Japanese Society for Cancer of the Colon and Rectum started a multi-institutional registry of colorectal cancer in 1980. The purpose of this report is to present an overview of the actual state of surgical and pathologic aspects of colorectal cancer treated in the leading hospitals in Japan.

MATERIALS AND METHODS: Registry files of clinical and pathologic findings for 38,369 patients treated between 1974 and 1986 with five-year follow-up information and 26,360 patients treated between 1991 and 1994 with no follow-up information were reviewed.

RESULTS: Numbers of registered patients have increased annually, reflecting a trend toward an increasing incidence of this cancer in Japan. Colon cancer increased more than rectal cancer in both genders. Resection of the primary lesion was achieved in more than 97 percent of patients who underwent surgical operation recently. The curative resection rate has improved from 65.1 to 79.1 percent for colon cancer and from 71.4 to 80.4 percent for rectal cancer between the 1974 and 1979 and the 1991 and 1994 periods, and operative mortality of those has decreased from 1.8 and 2 percent to 0.5 and 0.5 percent, respectively. There was a trend toward a decrease in locally advanced cancer in terms of cancer invasion into the bowel wall. Stage IV colon cancer also decreased from 22.9 to 16.6 percent with time. The five-year survival rate of each pTNM stage has gradually been improving and was especially evident for patients with Stages I, II, and III of rectal cancer. Overall five-year survival rates for colorectal cancer patients currently exceeds 60 percent.

CONCLUSION: The overall incidence of colorectal cancer and the ratio of colon cancer to rectal cancer patients in Japan are increasing. Results of surgical treatment are satisfactory with respect to curative resection rate, operative mortality, and the five-year survival rate. Registry data of the Japanese Society for Cancer of the Colon and Rectum are useful for reporting the actual state of diagnosis, treatment, and end results of colorectal cancer in Japan.