Temporal trends in the proportion cured for cancer of the colon and rectum: a population-based study using data from the Finnish Cancer Registry.

Colorectal cancer is the third most common cancer worldwide and the second most common cancer in Europe. Cumulative relative survival curves for both cancer of the colon and cancer of the rectum generally plateau after approximately 6-8 years. When this occurs, "population" or "statistical" cure is reached. We analyzed data from the Finnish Cancer Registry over a 50-year period using methods that simultaneously estimate the proportion of patients cured of disease (the cure fraction) and the survival time distribution of the "uncured" group. Our primary aim was to investigate temporal trends in the cure fraction and median survival of the uncured by age group for both cancer of the colon and rectum. For both cancers, the cure fraction has increased dramatically over time for all age groups. However, the difference in the cure fraction between age groups has reduced over time, particularly for cancer of the colon. Median survival in the uncured has also increased over time in all age groups but there still remains an inverse relationship between age and median survival, with shorter median survival with increasing age. The reasons for these impressive increases in patient survival are complex, but are highly likely to be strongly related to many improvements in cancer care over this same time period.