Take a second thought about lateral pelvic lymph node dissection of rectal cancer

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. Key words: Rectal neoplasms; Pelvic floor; Lateral pelvic lymph node dissection