Metachronous peritoneal carcinomatosis after curative treatment of colorectal cancer.

Introduction: Population-based data on metachronous peritoneal carcinomatosis (PC) after curative resection of colorectal origin are scarce. The aim of this study was to investigate the incidence of and risk factors for developing metachronous PC from colorectal cancer as well as survival since diagnosis of PC.
Methods: Data on metachronous metastases were collected between 2010 and 2011 for all patients diagnosed with M0 colorectal cancer between 2003 and 2008 in the Dutch Eindhoven Cancer Registry. Median follow-up was 5.0 years. Survival was defined as time from metastases diagnosis to death.
Results: Of the 5671 colorectal cancer patients, 1042 (18%) were diagnosed with metachronous metastases of whom 197 (19%) developed metachronous PC. The peritoneal surface was the only site of metastasis in 81 (41%) patients while 116 (59%) patients were diagnosed with both PC and metastases elsewhere. Median survival after diagnosis of PC was 6 months compared to 15 months for patients with distant metastases in other organs. Patients with an advanced primary tumour stage, positive lymph nodes at initial diagnosis, primary mucinous adenocarcinoma, positive resection margin and a primary tumour located in the colon were at increased risk of developing metachronous PC.
Conclusion: Of the colorectal cancer patients who developed metachronous metastases, approximately one fifth is diagnosed with PC. Prognosis of these patients is poor with a median survival of 6 months after diagnosis. Identifying patients at high risk for developing metachronous PC is important as it may contribute to more accurate patient information, tailor-made follow-up schemes, and more adequate treatment.
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