A population-based study on the prognostic impact of primary tumor sidedness in patients with peritoneal metastases from colon cancer.

Nadine L De Boer,Ignace H J T De Hingh,Cornelis Verhoef,Johannes H W De Wilt,Koen Rovers,Niels F M Kok,Alexandra R M Brandt‐Kerkhof,Philip H De Reuver,Eva V E Madsen,Jacobus W.A Burger,Amanda Bos

doi:10.1002/cam4.3243

Abstract

Primary tumor location is an established prognostic factor in patients with (metastatic) colon cancer. Colon tumors can be divided into left‐sided and right‐sided tumors. The aim of this study was to determine the impact of primary tumor location on treatment and overall survival (OS) in patients with peritoneal metastases (PM) from colon cancer. This study is a retrospective, population‐based cohort study. Records of patients diagnosed with colon cancer and synchronous PM, from 1995 through 2016, were retrieved from the Netherlands Cancer Registry (NCR). Data on diagnosis, staging, and treatment were extracted from the medical records by specifically trained NCR personnel. Information on survival status was updated annually using a computerized link with the national civil registry. In total, 7930 patients were included in this study; 4555 (57.4%) had a right‐sided and 3375 (42.6%) had a left‐sided primary tumor. In multivariable analysis right‐sided primary tumor was associated with worse OS (HR: 1.11, 95% CI 1.03‐1.19, P = .007). Of all patients diagnosed with PM, 564 (7.1%) underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS‐HIPEC). Patients with left‐sided primary tumors were more often candidates for CRS‐HIPEC (6.5% vs. 8.0%, P = .008). OS of patients with right‐ and left‐sided tumors who underwent CRS‐HIPEC did not significantly differ. In conclusion, primary right‐sided colon cancer was an independent prognostic factor for decreased OS in patients diagnosed with synchronous PM. In patients treated with CRS‐HIPEC location of the primary tumor did not influence survival.

Highlights

5% of all patients with primary colon cancer, present with synchronous peritoneal metastases (PM).[1]
After correction for possible confounders, multivariable analysis showed that a right-sided primary tumor was an independent prognostic factor for impaired survival (HR 1.11, 95% confidence intervals (CI) 1.03-1.19, P = .007)
This current study showed that patients with synchronous PM from right-sided colon cancer had a worse prognosis as

Summary

| INTRODUCTION

5% of all patients with primary colon cancer, present with synchronous peritoneal metastases (PM).[1]. Examples of risk factors for patients with PM associated with impaired survival include the extent of peritoneal disease, extraperitoneal metastases, advanced primary tumor stage, nodal metastases, poor tumor differentiation, and poor performance status.[10,11,12] Several studies have shown that primary tumor location is a prognostic factor in patients with (metastatic) colon cancer.[13,14,15,16] Colon tumors can be divided into left-sided and right-sided tumors. Right- and left-sided primary tumors differ in embryological origin (mid-gut vs hind-gut), bacterial flora and tumor biology (ie, mutational status and microsatellite instability (MSI)).[17,18,19] In patients with metastatic colon cancer it is known that patients with right-sided tumors have worse tumor response rates to treatment with systemic chemotherapy, in both an adjuvant and palliative setting, and impaired survival outcomes. Other studies have shown that in patients who underwent resection for liver metastases, right-sided primary tumor was independently associated with impaired outcomes as well.[20,21,22,23,24] little is known about the role of primary tumor location in patients with PM, and patients with PM undergoing CRSHIPEC.[25,26] The aim of this study was to assess the impact of the primary tumor location in all patients with PM of colon cancer on a population-based level

| METHODS

| RESULTS

| DISCUSSION

Findings

CONFLICT OF INTEREST