直肠淋巴流向的研究从1895年D. Gerota的研究开始，提出了直肠淋巴流向可以分为上、中、下三个方向，经过很多学者的进一步研究修正，现普遍认为侧方淋巴流向可以分为4个方向：1.前方，由膀胱下动脉，前列腺动脉，经闭孔动脉到髂总动脉；2.沿直肠中动脉到髂内动脉；3.沿着骶中动脉和骶外侧动脉到腹主动脉分叉部位；4.沿着直肠下动脉到髂内动脉。侧方淋巴结转移主要发生在低位直肠癌，浸润深度大于肌层者，而转移的侧方淋巴结并不包括在直肠癌全直肠系膜切除术（TME）范围之内。NCCN直肠癌诊疗指南中没有提及侧方淋巴结的概念，日本大肠癌规约则认为有适应证的低位直肠癌应行侧方淋巴结清扫术。西方学者认为直肠癌侧方淋巴结转移是全身疾病，侧方淋巴结清扫难以改善总体临床结局；日本学者则认为是局部疾病，对低位直肠癌规范手术为TME＋侧方淋巴结清扫。西方学者认为术前放化疗可替代侧方淋巴结清扫；东方学者则认为对于术前放化疗不敏感的直肠癌患者，侧方淋巴结清扫术仍不失为一个可供选择的治疗方案。低位直肠癌患者是否应行预防性盆腔侧方淋巴结清扫仍存在争议，但治疗性侧方淋巴结清扫术则是日本的直肠癌规范治疗。不少研究报道了腹腔镜侧方淋巴结清扫术的初步探索结果，认为其是安全有效的，但其与开放手术的远期肿瘤学结果对比仍需多中心随机对照研究验证。

D. Gerota first put forward a research about rectal lymphatic flow in 1895, which the lymph flow can be divided into three directions: the upper, middle and lower directions. After correction by the further study of other scholars, now it is generally believed that the lateral lymph flow can be divided into four directions: 1. The front direction, running from the bladder artery, prostate arteries, obturator artery to common iliac artery; 2. Running from middle rectal artery to internal iliac artery; 3. Along the middle sacral artery and the lateral sacral artery to the abdominal aortic bifurcation area; 4. Running from inferior rectal artery to internal iliac artery. Lateral lymph node metastasis occurs mainly in low rectal cancer, which tumor infiltration depth is deeper than the muscular layer. Lateral lymph nodes were not included in the range of TME radical operation for rectal cancer. NCCN guidelines for rectal cancer did not mention concept of lateral lymph nodes, while the Japanese Colorectal Cancer Classification (JCCC) held that lateral lymph nodes dissection should be performed in low rectal cancer if there were indications. Western scholars think that lateral lymph node metastasis is a disease, and lateral lymph node dissection is hard to improve long-term clinical outcome. Japanese scholars insist that lateral lymph node metastasis is local disease, and TME + lateral lymph node dissection was standard operation for low rectal cancer. Western scholars think that preoperative chemoradiotherapy can take the place of lateral lymph node dissection, while eastern scholars argue that lateral lymph node dissection is an alternative treatment options for the patients who is not sensitive for preoperative chemoradiotherapy. Whether prophylactic pelvic lateral lymph node dissection should be performed in patients with low rectal cancer remains controversial, however, therapeutic lateral lymph node dissection is standard therapy of rectal cancer in Japanese. Many studies reported an initial exploration about laparoscopic lateral lymph node dissection and showed that it is safe and effective, but multi-center randomized controlled trial are needed to confirm its long-term oncologic outcome.