Does Primary Tumor Side Matter in Patients with Metastatic Colon Cancer Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy?

BACKGROUND: Primary tumor location has been shown to be prognostic of overall survival (OS) in patients with both locally advanced and metastatic colorectal cancer. The impact of sidedness on prognosis has not been evaluated in the setting of peritoneal-only metastases treated with cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC).

METHODS: A retrospective review of prospectively maintained databases of patients with peritoneal surface malignancy undergoing CRS/HIPEC from three high-volume centers was performed.

RESULTS: A total of 115 patients with metastatic colon cancer to the peritoneum who underwent CRS/HIPEC with mitomycin C were identified. Fifty-one patients (45%) had left-sided primary tumors, and 64 (55%) had right-sided primary tumors. Patients with right-sided tumors were more likely to be older (median age 56 vs. 49 years, p = 0.007) and to have signet ring cell histology (17% vs. 4%, p = 0.026). Patients with right-sided tumors had median disease-free survival (DFS) and OS of 14 months (95% confidence interval [CI] 10.5-17.5) and 36 months (95% CI 27.4-44.6), respectively, versus 16 months (95% CI 11.0-21.0) and 69 months (95% CI 24.3-113.7) for those patients with left-sided tumors. On multivariate analysis, primary tumor side was an independent predictor of both DFS and OS.

CONCLUSIONS: In this study, there was a dramatic, clinically significant difference in OS between patients with right- and left-sided tumors, and primary tumor side was an independent predictor of DFS and OS. Primary tumor side should be considered in patient selection for CRS with or without HIPEC.