Conditional survival in advanced colorectal cancer and surgery

Recent data show patients with advanced colorectal cancer (CRC) are surviving longer. What is unknown is how specific treatment modalities affect long-term survival. Conditional survival, or survival prognosis based on time already survived, is becoming an acceptable means of estimating prognosis for long-term survivors. We evaluated the impact of cancer-directed surgery on long-term survival in patients with advanced CRC.

We used Surveillance, Epidemiology, and End Results data to identify 64,956 patients with advanced (Stage IV) CRC diagnosed from 2000-2009. Conditional survival estimates by stage, age, and cancer-directed surgery were obtained based on Cox proportional hazards regression model of disease-specific survival.

A total of 64,956 (20.1%) patients had advanced disease at the time of diagnosis. The proportion of those patients who underwent cancer-directed surgery was 65.1% (n = 42,176). Cancer-directed surgery for patients with advanced stage disease was associated with a significant improvement in traditional survival estimates compared to patients who did not undergo surgery (hazard ratio = 2.22 [95% confidence interval, 2.17-2.27]). Conditional survival estimates show improvement in conditional 5-y disease-specific survival across all age groups, demonstrating sustained survival benefits for selected patients with advanced CRC.

Five-year disease-specific conditional survival improves dramatically over time for selected patients with advanced CRC who undergo cancer-directed surgery. This information is important in determining long-term prognosis and will help inform treatment planning for advanced CRC.