Surgical Management of the Primary Tumor in Stage IV Colorectal Cancer: A Confirmatory Retrospective Cohort Study

Background: Observational studies have suggested that patients with stage IV colorectal cancer who undergo surgical resection of the primary tumor (SRPT) have better survival. Yet the results are not confirmed in the setting of a randomized controlled trial. Lack of randomization and failure to control prognostic variables such as performance status are major critiques to the findings of the observational studies. We previously have shown that SRPT, independent of chemotherapy and performance status, improves survival of stage IV CRC patients. The current study aims to validate our findings in patients with stage IV CRC who were diagnosed during the period of modern chemotherapy.

Methods: A cohort of 569 patients with stage IV CRC diagnosed during 2006-2010 in the province of Saskatchewan was evaluated. Cox regression model was used for the adjustment of prognostic variables.

Results: Median age was 69 years (59-95) and M: F was 1.4:1. Fifty-seven percent received chemotherapy, 91.4% received FOLFIRI or FOLFOX & 67% received a biologic agent. Median overall survival (OS) of patients who underwent SRPT and received chemotherapy was 27 months compared with 14 months of the non-resection group (p<0.0001). Median OS of patients who received all active agents and had SRPT was 39 months (95%CI: 25.1-52.9). On multivariate analysis, SRPT, hazard ratio (HR):0.44 (95%CI: 0.35-0.56), use of chemotherapy, HR: 0.33 (95%CI: 0.26-0.43), metastasectomy, HR: 0.43 (95%CI: 0.31-0.58), second line therapy, HR: 0.50 (95%CI: 0.35-0.70), and third line therapy, HR: 0.58 (95%CI: 0.41-0.83) were correlated with superior survival.

Conclusions: This study confirms our findings and supports a favorable association between SRPT and survival in patients with stage IV CRC who are treated with modern therapy.