Rectal cancer survival in the Nordic countries and Scotland.

The aim of this study was to present detailed population-based survival estimates for patients with a rectal adenocarcinoma, using cancer register data supplemented with clinical data. Based on cancer register data, differences in rectal cancer survival have been reported between countries in Europe. Variation in the distribution of stage at diagnosis, initial therapy including surgical technique, and comorbidity are possible explanatory factors. Adenocarcinomas in the rectum, diagnosed in 1997 and identified in the national cancer registries in the Nordic countries and Scotland were included. Age standardized 5-year relative survival and multiplicative regression models for the relative excess mortality were calculated. 3888 patients were included in the survival study. Men in Denmark, Finland and Iceland had lower 5-year relative survival and poorer stage distribution compared to Norway, Sweden and Scotland. Danish men had the highest rate of excess deaths in the first six months after diagnosis. Stage adjusted, the elevated relative excess mortality decreased and after six months the excess mortality rates were the same in all countries. The poor 5-year relative survival in Danish men was mainly due to a high excess rate of death during the first six months after diagnosis. The low survival in Finland and Iceland was not in accordance with other periods. For both countries this may be explained by random variation due to small numbers. The study emphasizes the need for high quality and detailed data in order to understand international survival differences, and cautions comparisons between large national samples and those of smaller areas.