PURPOSE: Elderly patients with colorectal cancer undergo surgery with curative intent less frequently than younger patients, and survival declines with increasing age. We compared relative survival of colorectal cancer among patients older than 75 years with that of younger patients in Denmark during the period 1977 to 1999. We also examined trends in choice of initial treatment. METHODS: From the files of the nationwide population- based Danish Cancer Registry, we identified all cases of colorectal cancer diagnosed between 1977 and 1999. We then linked this data to information on survival obtained from the Danish Register of Causes of Death and from the Central Population Register. RESULTS: During the entire study period, short- term and long- term relative survival improved for patients of all ages, but the improvement was more pronounced among elderly patients ( > 75 years). Radical resection was increasingly chosen as the initial treatment for elderly patients; during the 1995 to 1999 period it was performed on approximately 50 percent of such patients, almost as frequently as among younger patients. CONCLUSIONS: Relative survival of elderly colorectal cancer patients ( > 75 years) improved in Denmark between 1977 and 1999. In the most recent period studied, 1995 to 1997, only minor differences in five- year relative survival were observed among younger, middle- aged, and elderly patients. A simultaneous increase in the rate of radical resection among elderly patients, reflecting more effective treatment, may underlie this finding. PURPOSE: Elderly patients with colorectal cancer undergo surgery with curative intent less frequently than younger patients, and survival declines with increasing age. We compared relative survival of colorectal cancer among patients older than 75 years with that of younger patients in Denmark during the period 1977 to 1999. We also examined trends in choice of initial treatment. METHODS: From the files of the nationwide population-based Danish Cancer Registry, we identified all cases of colorectal cancer diagnosed between 1977 and 1999. We then linked this data to information on survival obtained from the Danish Register of Causes of Death and from the Central Population Register. RESULTS: During the entire study period, short- term and long- term relative survival improved for patients of all ages, but the improvement was more pronounced among elderly patients (> 75 years). Radical resection was increasingly chosen as the initial treatment for elderly patients; during the 1995 to 1 999 period it was performed on approximately 50 percent of such patients, almost as frequently as among younger patients. CONCLUSIONS: Relative survival of elderly colorectal cancer patients (> 75 years) improved in Denmark between 1977 and 1999. In the most recent period studied, 1995 to 1997, only minor differences in five- year relative survival were observed in younger, middle- aged, and elderly patients. A simultaneous increase in the rate of radical resection among elderly patients, reflecting more effective treatment, may underlie this finding.