Changes in colorectal cancer during a 20-year period: an extended report from the multi-institutional registry of large bowel cancer, Japan.

ABSTRACT

PURPOSE: This study was designed to examine trends of colorectal cancer in relation to age, gender, site, and survival during the past 20 years. METHODS: The multi-institutional registry of the Japanese Society for Cancer of the Colon and Rectum offered 87,695 surgical cases with invasive adenocarcinoma during 1978 to 1997 for analysis. We calculated survival rates and used the Cox's proportional hazard model for cases during 1978 to 1994. RESULTS: The number of cases showed a 2.5-fold increase with consistent male predominance confined to the distal colon and the rectum. Colon cancer in the last five-year period was more likely right-sided for females (odds ratio, 1.26; 95 percent confidence interval, 1.16-1.38) and males (odds ratio, 1.16; 95 percent confidence interval, 1.06-1.25) compared with the first period. Cancers in younger patients were more likely at Stage III to IV in the late 1990s if the cancers were in the distal colon, the rectum (for both genders), or the proximal colon (for females). Survival was improved except for cases with proximal colon cancer of Stage IV. In the multivariate analysis, hazard ratios for death in the postoperative five years were 0.77, 0.59, and 0.66 for proximal colon, distal colon, and rectal cancers, respectively, in the last period as compared with those in the first period [corrected]. Reduced hazard ratio for females was the largest for proximal colon cancer with Stage I to II. CONCLUSION: Although surgical outcome was largely improved, delayed presentation or diagnosis in younger patients remained a problem. Preferential localization in the proximal colon and survival benefit for females should be investigated.