Rectal cancer: The impact of lymph node dissection and preoperative radiation in the era of total mesorectal excision

Background: The question of adequate lymphadenectomy and application of preoperative radio(chemo)therapy in the era of total mesorectal excision (TME) in rectal cancer has been discussed in recent years without a definitive conclusion. Methods: Review of the literature. Results: Lymph node metastases (pN) and the lymph node ratio are established prognostic factors in rectal cancer. Therefore, lymphadenectomy has a major impact in rectal cancer surgery. Depending on the tumor location, lymphadenectomy should include the partial or complete removal of the mesorectum in addition to the complete resection of the tumor-bearing rectum segment. The mesorectum includes the regional lymphatic drainage; with the mesorectal fascia it defines the circumferential extent of lymphadenectomy. The aboral lymphadenectomy should reach 5 cm below the macroscopic tumor edge (PME) for tumors of the proximal rectal third, and the complete mesorectum (TME) in the middle and distal third. The oral lymphadenectomy should be performed along the inferior mesenteric artery at least until the branch of the left colic artery. According to the literature, no recommendation exists for routine lateral or extended lymphadenectomy. Official guidelines recommend preoperative radio(chemo)therapy for the treatment of UICC stages II and III rectal cancer in the era of total mesorectal excision. Several studies have shown, however, that preoperative radiation does not improve survival. Side effects were tolerated to prevent a local recurrence in some patients. Conclusions: Better selection for preoperative radiation is desirable, because in the era of TME and with experienced rectal cancer surgeons the majority of patients do not benefit from radiation therapy.