Maroney S, et al. - This study was performed to investigate whether resection of the primary tumor in patients undergoing chemotherapy for stage IV colorectal cancer with unresected metastasis was correlated with improved survival. The researchers revealed that after adjusting for confounding variables, definitive resection of the primary site was associated with improved overall survival in these patients.

Methods

• From 2004 to 2012, the researchers performed a retrospective cohort study of the National Cancer Data Base.
• They included all patients with synchronous metastatic colorectal adenocarcinoma, who were treated with systemic chemotherapy.
• The study groups were patients who underwent definitive surgery for the primary tumor and those who did not.
• Patients who had surgical intervention on the sites of metastasis or pathology other than adenocarcinoma were excluded.
• Overall survival was the primary outcome.

Results

• In this study, 55% underwent surgical resection of the primary site among the 65,543 patients with unresected stage IV colorectal adenocarcinoma undergoing chemotherapy.
• Improved median survival was observed in patients who underwent surgical resection of the primary tumor compared to patients treated with chemotherapy alone (22 vs 13 months, p < .0001).
• For patients who were treated with either multi-agent or single-agent chemotherapy, the surgical survival benefit was present (23 vs 14 months, p < 0.001; 19 vs 9 months, p < 0.001).
• When using multivariate analysis with propensity score matching, surgical resection of the primary tumor was also associated with improved survival (OR = 0.863; 95% CI [0.805-.924]; HR = 0.914; 95% CI [0.888-0.942]).