Estimating population-based recurrence rates of colorectal cancer over time in the United States

Abstract

Background:Population-based metastatic recurrence rates for patients diagnosed with non-metastatic colorectal cancer (CRC) cannot be estimated directly from population-based cancer registries because recurrence information is not reported. We derived population-based CRC recurrence rates using disease-specific survival data based on our understanding of the CRC recurrence-death process. Methods:We used a statistical continuous-time multistate survival model to derive population-based annual CRC recurrence rates from 6 months to 10 years after CRC diagnosis using relative survival data from the Surveillance, Epidemiology, and End Results Program. The model was based on the assumption that, after 6 months of diagnosis, all CRC-related deaths occur only in patients who experience a metastatic recurrence first, and that the annual CRC-specific death rate among patients with recurrence was the same as in those diagnosed with de novo metastatic disease. We allowed recurrence rates to vary by post-diagnosis time, age, stage, and location for two diagnostic time periods. Results:In patients diagnosed in 1975-1984, annual recurrence rates 6 months-5 years post-diagnosis ranged from 0.054-0.060 in stage II colon cancer, 0.094-0.105 in stage II rectal cancer, and 0.146-0.177 in stage III CRC, depending on age. We found a statistically significant decrease in CRC recurrence among patients diagnosed in 1994-2003 compared with those diagnosed in1975-1984 for 6 months-5 years post-diagnosis (hazard ratios between 0.43-0.70). Conclusions:We derived population-based annual recurrence rates of CRC in the US for up to 10 years post-diagnosis using relative survival data. Impact:Our estimates can be used in decision-analytic models to facilitate analyses of CRC interventions that are more generalizable.