The impacts of surgery of the primary cancer and radiotherapy on the survival of patients with metastatic rectal cancer

The role of surgery of the primary cancer and radiation in metastatic colorectal cancer (mCRC) is still controversial currently, and evidence implied that colon cancer (CC) and rectal cancer (RC) should be treated with difference. Hence we focused on metastatic rectal cancer (mRC) solely to compare the cancer cause-specific survival (CSS) of patients receiving varied treatments of the primary cancer: no treatment, surgery only, radiation only, and surgery plus radiation, based on the records of the Surveillance, Epidemiology, and End Results (SEER) database. A total of 8669 patients were included. Results demonstrated that the 2-year CSS was 28.1% for no treatment group, 30.7% for only radiation group, 50.2% for only surgery group, and 66.5% for surgery plus radiation group, reaching statistical difference (P < 0.001). Furthermore, the CSSs of mRC patients in the surgery group were similar regardless of resection ranges (P = 0.44). Besides, we analyzed the prognostic factors for mRC and found carcinoembryonic antigen (CEA) level, metastasis (M) stage, Tumor (T) stage, tumor size, differentiate grade, age and marital status should be taken into consideration when estimating the prognosis. Particularly, patients with normal CEA level or M1a stage showed a significant survival advantage. Overall, present study suggested that surgery of the primary cancer and radiation might help to improve the survival of mRC patients, especially when both treatments were conducted. Our results may assist clinicians to make better treatment strategy for patients with mRC.