Background: Conditional survival (CS) is a relevant prognostic measure and may be particularly important for young adult patients with colorectal cancer (CRC), whose incidence is rising. We sought to compare CS among young versus older adults with CRC.
Methods: Patients diagnosed with CRC between 2004 and 2010 were identified from the Surveillance, Epidemiology, and End Results registry. Smoothed yearly hazards of death due to CRC, other causes and any cause were estimated, stratified by age at diagnosis (below 50 vs. 50 y and above) and stage (I-III vs. IV). Stage-specific conditional 5-year overall survival and cancer-specific survival given that patients had already survived 1 to 5 years after diagnosis was calculated.
Results: Among 161,859 patients with median follow-up of 54 months, 35,411 (21.9%) were aged below 50 years. For older adults with nonmetastatic CRC, hazards of death due to noncancer causes exceeded that of rectal and colon cancer ∼6.1 and 3.8 years after diagnosis, respectively. Patients experienced improved CS over time with greater improvement seen for more advanced stages. However, young adults had less CS improvement over time than older adults. For example, the 5-year cancer-specific survival for stage IV colon cancer improved from 15.6% to 77.2% (change=61.6%) 0 to 5 years after diagnosis for older adults but only 20.3% to 67.7% (change=47.4%) for young adults.
Conclusions: Prognosis for CRC improves over time for all patients, although the increase in survival appears to be less for young than older adults. Up to 10 years after diagnosis, the primary cause of death in young adults with CRC remains their incident cancer.