L. M. Wancata1, M. Banerjee4, D. G. Muenz4, M. R. Haymart5, S. L. Wong3 1University Of Michigan,Department Of General Surgery,Ann Arbor, MI, USA 3University Of Michigan,Division Of Surgical Oncology,Ann Arbor, MI, USA 4University Of Michigan,Department Of Biostatistics,Ann Arbor, MI, USA 5University Of Michigan,Division Of Metabolism, Endocrinology, & Diabetes & Hematology/Oncology,Ann Arbor, MI, USA
Introduction: Though historically associated with poor survival rates, recent data demonstrate that some patients with advanced (stage IV) colorectal cancer (CRC) are surviving longer in the modern era. Treatments have included improvements in systemic therapies and increased use of metastasectomy. Traditional survival estimates are less useful for longer-term cancer survivors and conditional survival, or survival prognosis based on time already survived, is becoming more accepted as a means of estimating prognosis for certain subsets of patients who live beyond predicted survival times. What is unknown is how specific treatment modalities affect survival. We evaluated the use of cancer-directed surgery in patients with advanced CRC to determine its impact on long term survival in this patient population.
Methods: We used data from the Surveillance, Epidemiology, and End Results (SEER) registry to identify 323,415 patients with CRC diagnosed from 2000-2009. The SEER program collects data on patient demographics, tumor characteristics, treatment, and survival data from cancer registries across the country. This cohort represents approximately 26% of the incident cases and its demographics are comparable to that of the general US population. Conditional survival estimates by SEER stage, age and cancer-directed surgery were obtained based on Cox proportional hazards regression model of disease-specific survival.
Results: Of the 323,415 patients studied 64,956 (20.1%) had distant disease at the time of diagnosis. Median disease-specific survival for this cohort was just slightly over 1 year. The proportion of patients with distant disease who underwent cancer-directed surgery was 65.1% (n=42,176). Cancer-directed surgery in patients with distant disease appeared to have a significant effect on survival compared to patients who did not undergo surgery [hazard ratio 2.22 (95% CI 2.17-2.27)]. These patients had an approximately 25% improvement in conditional 5 year disease specific survival across all age groups as compared to their counterparts who did not receive cancer-directed surgery, demonstrating sustained survival benefits for selected patients with advanced CRC who undergo resection. A significant improvement in conditional survival was observed over time, with the greatest gains in patients with distant disease compared to those with localized or regional disease (Figure).
Conclusion: Five-year disease-specific conditional survival improves dramatically over time for selected patients with advanced stage CRC who undergo cancer-directed surgery. This information is important in determining long term prognosis associated with operative intervention and will help inform treatment planning for patients with metastatic disease.
