Conditional survival analysis of stage IV colorectal cancer patients living >24 months.

Abstract

3566 Background: The overall survival of patients with stage IV colorectal cancer (both in unresectable and resectable settings) has been increasing over recent decades due to improvements in chemotherapy, liver surgery and other liver-directed therapies. As a result of more patients living longer, there is a need to refine prognostic information to more accurately predict survival to assist multi-disciplinary cancer management teams in treatment decisions but also for patient quality of life. Methods: We performed a retrospective analysis of all patients with stage IV colorectal cancer seen at Rutgers Cancer Institute of New Jersey between Jan 1, 2005 to March 10, 2015 by ICD-9 code (N = 318 patients). This included patients who were deemed unresectable and patients who were resected with curative intent. Our study population was patients with documented survival for > 24 months (N = 158). Variables gathered included patient demographics, disease related (primary location, KRAS status, metastasis location, interval to metastases) and treatment related (chemotherapy regimens, radiation and surgery) data. Survival curve estimates are conditional on having survived 24 months. Results: Complete data was available for 125 patients (75 were resected for cure and 50 were not). Median overall survival of resected patients was not reached. The median overall survival of non-resected patients was 75.9 months. Univariate and multivariate analysis for surgery and non-surgery groups was performed. No statistically significant covariates were found beyond surgical resectability. The conditional survival probabilities of living 1, 2 or 3 years longer after 24 months of survival are 91.7%, 71.6% and 51.6% respectively in the patients with unresectable disease, and 98.1%, 92.2% and 88.8% in patients who were able to be resected with curative intent. Conclusions: These results indicate that patients who survive 24 months with stage IV colorectal cancer have an excellent prognosis. For patients who are unresectable and survive 24 months, this study suggests that they may benefit from resection of remaining metastatic sites if feasible. For resected patients this information may propose a possible benefit from repeat metastasectomy.