[Comment] Risk of metachronous peritoneal metastases after surgery for obstructive colon cancer: multivariate analysis from a series of 1,085 patients

[Background] Data in the literature suggest that obstruction is an independent predictor of poor prognosis in colon cancer. Of all possible sites of recurrence, peritoneal metastases are associated with worse survival. Our aim was to report the incidence of metachronous peritoneal metastases from a cohort of patients undergoing resection of obstructive colon cancer with curative intent and to identify predictive factors for metachronous peritoneal metastases. [Methods] From 2000 to 2015, a total of 2,325 patients were treated for obstructive colon cancer in French surgical centers, members of the French National Surgical Association (AFC). Patients with palliative management, synchronous metastatic disease, and with postoperative mortality were excluded. A multivariate analysis was performed to determine independent predictive factors of metachronous peritoneal metastases. [Results] The cohort included 1,085 patients. The median follow-up was 21.5 months. Metachronous peritoneal metastases occurred in 12% of patients and were diagnosed after a median interval of 13.5 months. The cumulative 3-year metachronous peritoneal metastasis rate was 10.9%. Three-year overall survival was 85% for patients who did not develop recurrence, 71% for those who develop recurrence without peritoneal metastases, and 56% for those with metachronous peritoneal metastases (P<0.001). In multivariate analysis, 3 variables were identified as independent risk factors for metachronous peritoneal metastases: pT4 stage (odds ratio: 1.98;95% confidence interval: 1.17-3.36; P=0.011), pN2 stage (odds ratio: 2.57; 95% confidence interval: 1.89-4.45; P<0.001), and fewer than 12 lymph nodes examined (odds ratio: 2.01; 95% confidence interval: 1.08-3.74; P=0.028). [Conclusion] This study showed a significant risk of metachronous peritoneal metastases after curative-intent resection of obstructive colon cancer. The awareness of factors predisposing to metachronous peritoneal metastases could improve the treatment strategy of these patients.