Liu Q, et al. - Whether circumferential resection margin (CRM) can be considered a prognostic factor for long-term oncologic survival following rectal cancer surgery was investigated in this study. Patients from the Surveillance, Epidemiology, and End Results (SEER) program diagnosed with malignant rectal cancer between January 1, 2010 and December 31, 2014 were included. Findings revealed that the CRM offers independent prognostication in rectal cancer, and surgeons should try to maximize the CRM. A 99% increased risk of cancer-specific mortality, was independently associated with a circumferential resection margin ≤ 1 mm in rectal cancer. More postoperative attention, depending on individual situation, was recommended for rectal cancer patients with CRM ≤ 1 mm. Also, accurate measurement of CRM in millimeters in a preoperative magnetic resonance imaging or pathological report was recommended, rather than simply describing it as “involved” or “clear.”