Metachronous peritoneal metastases following curative resection for colon cancer: Understanding risk factors and patterns of recurrence

BACKGROUND A subset of metachronous colon cancer recurrence manifests as peritoneal metastases (PM). Risk factors for metachronous PM recurrence are not well-defined in patients with stage II or III colon cancers after curative resection and standard adjuvant treatments. METHODS Population data from the California Cancer Registry for patients with Stage II or III colon cancer were collected between 2004 and 2012. Multivariate analysis was used to identify factors associated with metachronous PM. RESULTS Of the 2077 patients with stage II or III colon cancer, female patients (odds ratio [OR] = 1.84, p = 0.02), T4 primary tumor (OR = 2.36, p = 0.02), mucinous (OR = 3.97, p < 0.01) or signet-ring histology (OR = 6.01, p = 0.01), and right-sided cancer (OR = 2.2, p < 0.01) were found with increased risk of metachronous isolated PM recurrence after curative resection. Median survival after diagnosis for patients without PM recurrence was 22 months, compared with 12 months for PM recurrence (p < 0.001). CONCLUSION PM recurrence groups have a worse overall survival than patients with recurrent disease in other sites. A better understanding of the tumor biology and molecular characteristics of colon cancers likely to recur as PM is needed to explain behavior and identify potential targeted therapy.