Prognostic differences between oligometastatic and polymetastatic disease after resection in patients with colorectal cancer and hepatic or lung metastases: Retrospective analysis of a large cohort at a single institution

Background: Long-term survival data are lacking, and prognostic factors are not well-defined for patients with colorectal cancer and hepatic or lung metastases. This study evaluated the outcomes after resection of oligometastatic hepatic or lung metastases from colorectal cancer and sought to identify prognostic factors. Methods: We retrospectively investigated 1,123 patients with colorectal cancer and hepatic or pulmonary metastases who underwent curative surgery between January 1991 and December 2016. Results: Of the 1,123 patients, 719 had hepatic metastases, 287 had pulmonary metastases, and 117 had both. The 5-year overall survival rate was 52.3% in the hepatic metastases group, 70.4% in the pulmonary metastases group, and 71.4% in the hepatic and pulmonary metastases group (P < .001). In total, 1,045 patients had oligometastases (1-5 metastatic lesions in 1 or 2 organs) and 78 had polymetastases (>= 6 metastases in 1 or 2 organs). Prognosis was significantly better in patients with oligometastases than in those with polymetastases. The 5-year overall survival rate was 59.0% in the oligometastases group and 35.3% in the polymetastases group (P < .001); the respective 5-year relapse-free survival rates were 37.5% and 11.6% (P < .001). Multivariable analysis identified predictors of both poor overall survival and relapse-free survival to be a high carcinoembryonic antigen level before the first metastasectomy, largest metastasis measuring >= 2 cm, polymetastases, and synchronous metastases. Conclusion: Prognosis after curative resection was better in patients with oligometastatic colorectal cancer in the liver or lung than in those with polymetastases. Multidisciplinary decision-making strategies, including about surgery, should be based on number of metastases rather than their site. (c) 2022 Elsevier Inc. All rights reserved.