Improvement of survival over time for colon cancer patients by anatomical sub-sites

The aims of this study are to describe and to evaluate improvement of survi val over time for colon cancer patients by anatomical sub-sites. Data on 66 1 patients newly diagnosed as having colon cancer at Osaka Medical Center f or Cancer and Cardiovascular Diseases from 1978 to 1991 were examined in th is study. Corrected survival was calculated with the Kaplan-Meier method ac cording to the period of diagnosis: early period (1978-84) and later period (1985-91), Factors concerning the difference in survival between the two p eriods were examined with the Cox proportional hazards regression model acc ording to sub-site. Five-year corrected survival of the patients with left colon cancer improved significantly (60 to 72%; P<0.01), probably due to ad vances in treatment, while that of patients with transverse colon cancer al so improved significantly (39 to 67%; P<0.01), mainly because of progress i n diagnosis. The five-year corrected survival of those with right colon can cer did not increase (57 to 46%; P=0.14), owing to lack of improvement in s tage at diagnosis. Among the three sub-sites, the right showed the worst fi ve-year survival in the later period. We concluded that survival of patient s with right colon cancer, differing from the other anatomical sub-sites, d id not improve, possibly because of lack of symptoms. The screening program s for colon cancer introduced in Japan in 1992 may be expected to improve t he survival of patients with colon cancer, including that of the right colo n.