Aim: With the increase in the number of long-term colorectal cancer (CRC) survivors, there is a growing need for subgroup-specific analysis of conditional survival.
Methods: All 137,030 stage I-III CRC patients diagnosed in the Netherlands between 1989 and 2008 aged 15-89 years were selected from the Netherlands Cancer Registry. We determined conditional 5-year relative survival rates, according to age, subsite and tumour stage for each additional year survived up to 15 years after diagnosis as well as trends in absolute risks for and distribution of causes of death during follow-up.
Results: Minimal excess mortality (conditional 5-year relative survival >95%) was observed 1 year after diagnosis for stage I colon cancer patients, while for rectal cancer patients this was seen after 6 years. For stage II and III CRC, minimal excess mortality was seen 7 years after diagnosis for colon cancer, while for rectal cancer this was 12years. The differences in conditional 5-year relative survival between colon and rectal cancer diminished over time for all patients, except for stage III patients aged 60-89 years. The absolute risk to die from CRC diminished sharply over time and was below 5% after 5 years. The proportion of patients dying from CRC decreased over time after diagnosis while the proportions of patients dying from other cancers, cardiovascular disease and other causes increased.
Conclusion: Prognosis for CRC survivors improved with each additional year survived, with the largest improvements in the first years after diagnosis. Quantitative insight into conditional relative survival estimates is useful for caregivers to inform and counsel patients with stage I-III colon and rectal cancer during follow-up.
Keywords: Cause of death; Colorectal cancer; Conditional survival; Long-term survivors; Subsite.
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