The impact of old age on cancer-specific and non-cancer-related survival following elective potentially curative surgery for Dukes A/B colorectal cancer

Previous studies have suggested that survival following surgery for colorectal cancer is poorer in the elderly. However, the findings were inconsistent and none of the studies adjusted for case mix. The aim of this study was to establish whether there were age-related differences in cancer (colorectal)-specific and non-cancer (colorectal)-related survival in patients undergoing elective potentially curative resection for Dukes stage A/B colorectal cancer. One thousand and forty three patients who underwent elective potentially curative resection for Dukes' A/B colorectal cancer between 1991 and 1994 in 11 hospitals in Scotland were included in the study. Ten year cancer-specific and non-cancer-related survival and the hazard ratios were calculated according to age groups (<64; 65-74/>74 years). On follow-up 273 patients died of their cancer and 328 died of non-cancer-related causes. At 10 years, overall survival was 45%, cancer specific was 70% and non-cancer-related survival was 64%. On multivariate analysis of all factors, age (HR 1.38, 95% CI 1.18-1.62, P<0.001), sex (HR 1.74, 95% CI 1.36-2.23, P<0.001), site (HR 1.42, 95% CI 1.11-1.81, P<0.01) and Dukes' stage (HR 1.71, 1.19-2.47, P<0.01) were independently associated with cancer-specific survival. On multivariate analysis of all factors, age (HR 2.14, 1.84-2.49, P<0.001), sex (HR 1.43, 1.15-1.79, P<0.01) and deprivation (HR 1.30, 1.09-1.55, P<0.01) were independently associated with non-cancer-related survival. The results of this study show that increasing age impacts negatively both on cancer-specific and non-cancer-related survival following elective potentially curative resection for node-negative colorectal cancer. However, the effect of increasing age is greater on the non-cancer-related survival. These results suggest that cancer-specific and non-cancer-related mortality should be considered separately in survival analysis of these cancer patients.