Subdivision of metastatic colorectal cancer for identifying patients who benefit more from primary tumor resection

Background Stage IV colorectal cancer (CRC) patients are heterogeneous with distinctive clinicopathologic features and prognosis. Radical resection of primary tumor and distant metastases is associated with improved survival outcomes in metastatic CRC. The value of palliative primary tumor resection is controversial. The present study explored which subgroups benefited more from primary tumor resection in metastatic CRC. Methods Between 2004 and 2015, patients with metastatic CRC were identified using the surveillance, epidemiology, and end results (SEER) database. Uni- and multivariable Cox regression analysis were performed to identify factors associated with decreased cancer-specific mortality. The subgroups were divided based on the independent prognostic factors. Results Age, marital status, race, serum CEA, histologic type, differentiation, tumor location, surgery of primary or metastatic lesion, site of metastases, number of metastatic sites, chemotherapy and radiotherapy were identified as independent prognostic factors. Patients with non-white race, normal serum CEA, non-signet ring cell carcinoma, well or moderate differentiation, surgery of metastases, isolated liver metastasis, single metastasis, receiving chemotherapy or radiotherapy presented more survival benefit from primary tumor resection. Conclusion Subgroup of metastatic CRC optimizes decision-making and selected patients will benefit more from primary tumor resection.