Abstract:Radical resection of mid- and low-rectal cancer requires not only oncologic safety but also preservation of organs and postoperative bowel function. While a 1-2 cm distal resection margin has been largely accepted, the optimal length of the proximal margin remains highly controversial. Clinically, the "10-cm rule" derived from colon cancer is often referenced, yet its applicability to rectal cancer lacks consistent supporting evidence. Previous studies have shown that an excessively long proximal margin may increase anastomotic tension and lead to anastomotic leakage, whereas insufficient resection heightens the risk of positive margins and local recurrence. In addition, the extent of lymph node metastasis, vascular perfusion of the proximal bowel, radiation-induced injury after neoadjuvant chemoradiotherapy, and postoperative bowel function-particularly low anterior resection syndrome-are all important factors influencing the selection of the proximal margin. In recent years, the application of indocyanine green fluorescence imaging has provided new evidence for intraoperative assessment of bowel perfusion; for patients receiving neoadjuvant chemoradiotherapy, radiation injury presents a gradient pattern, and resecting approximately ≥20 cm proximal to the tumor may reduce the incidence of anastomosis-related complications. Based on current literature, this review provides a systematic overview of the historical evolution, influencing factors, and clinical evidence regarding proximal resection margins in rectal cancer surgery, with the aim of informing individualized margin selection and optimizing surgical strategies.