Minimal excess mortality for long-term colon cancer survivors in the Netherlands 1989-2008

We determined conditional 5-year relative survival rates for colon cancer patients, according to age, gender and tumour stage for each additional year of survival up to 15 years after diagnosis. All 89,451 patients diagnosed in the Netherlands with colon cancer stage I-III in 1989-2008 aged 15-89 years were selected from the Netherlands Cancer Registry. Conditional 5-year relative survival was computed for every additional year of survival up to 15 years. There was minimal excess mortality (conditional 5-year relative survival >95%) 1-4 years after diagnosis of stage I patients and 4-7 years after diagnosis of stage II patients, with patients aged 45-74 years reaching this point later compared to both younger and elderly patients. For stage III patients, minimal excess mortality was observed 5 years after diagnosis for those aged 75-89 years, but it remained elevated up to 13 years after diagnosis for those aged 15-44 years. Initial differences in relative survival at diagnosis between age and stage groups largely disappeared with increasing number of years survived. The prognosis for colon cancer survivors improved with each additional year survived. In the first years after diagnosis conditional survival improved largely for all colon cancer patients, especially for stage III patients. There was minimal excess mortality for colon cancer patients stage I-III at some point within 15 years of diagnosis, being later for more advanced stages. Quantitative insight into conditional survival for cancer patients is useful for caregivers to help plan optimal cancer surveillance and inform patients about their prognosis.