Prognostic value of distant metastasis sites and surgery in stage IV colorectal cancer: a population-based study

Purpose We investigated the prognostic value of distant metastasis sites among patients with metastatic colorectal cancer (CRC) and the significance of metastasectomy and resection of the primary CRC. Methods Between 2010 and 2014, patients diagnosed with metastatic colorectal adenocarcinoma were selected using the surveillance, epidemiology, and end results (SEER) database. The prognosis of these patients was compared according to the site of metastasis (liver, lung, bone, and brain). A total of 15,133 patients suffered from isolated organ involvement, while 5135 patients experienced multiple organ metastases. Results In the isolated organ metastasis cohort, median overall survival (OS) for patients with liver, lung, bone, and brain metastases was 16, 20, 7, and 5 months, respectively. Patients with isolated lung metastases had better cancer-specific survival (CSS) and OS as compared to patients with metastases at any other sites ( p < 0.0001 for both CSS and OS). Patients with isolated liver metastases had better prognosis as compared to patients with isolated bone or brain metastases ( p < 0.0001 for both CSS and OS). Moreover, patients with a single metastatic site had better prognosis than patients with multiple organs involved ( p < 0.0001 for both CSS and OS). Multivariate analysis in patients with isolated organ metastases demonstrated that age ≤ 60 years, rectal cancer, being married, non-black race, N0 stage, and surgery of the primary and distant lesions showed more favorable prognosis. Conclusions The metastatic site was an independent prognostic factor in stage IV colorectal cancer. Also, carefully chosen patients may benefit from surgery.