Colorectal cancer survival trends in Norway 1958-1997.

The purpose of this study was to examine the pattern of survival for colorectal adenocarcinoma (CRC), and to investigate the prognostic factors for the disease. In the analysis, 50993 cases of CRC aged 40-84 years, diagnosed between 1958 and 1997 in Norway, were included. Esteve's relative survival method was used, together with a time trend analysis, conducted by least-squares linear regression. Cox proportional hazards regression analysis was used to examine cause-specific mortality. Five-year relative CRC survival has increased by an estimated 3% per 5-year diagnostic period. In 1958-1962, relative survival was about 40% for both males and females, and increased to 56 and 60%, respectively, in 1993-1997. Rectal cancer had a higher cause-specific mortality (RR 1.26, 95% CI 1.22-1.30) than proximal colon (reference) and distal colon (RR 0.97, 95% CI 0.93-1.00 cancers), while females had a lower cause-specific mortality than males (RR 0.88, 95% CI 0.86-0.90). The increase in the relative survival rate in Norway is probably due to improved treatments and advanced diagnostics. Norway has a higher CRC survival rate than the EUROCARE average.