Is the routine dissection of lateral lymph nodes really necessary after mesorectal excision for clinical stageII/III lower rectal cancer?

We have read with extremely interest the article of Fujita et al. “Mesorectal Excision With or Without Lateral Lymph Node Dissection for Clinical Stage II/III Lower Rectal Cancer (JCOG0212) A Multicenter, Randomized Controlled, Noninferiority Trial” published on Annals of Surgery. The guidelines of Japanese Society for Cancer of the Colon and Rectum (JSCCR) for the treatment of colorectal cancer recommend lateral lymph node dissection (LLND) for clinical Stage II/III Lower Rectal: “Lateral lymph node dissection is indicated when the lower border of the tumor is located distal to the peritoneal reflection and the tumor has invaded beyond the muscularis propria”. In effect, a study of JSCCR reported that “the incidence of lateral lymph node metastasis was 20.1% among patients whose lower rectal tumor border was located distal to the peritoneal reflection and whose cancer invaded beyond the muscularis propria. After performing lateral lymph node dissection for this indication, it is expected that the risk of intrapelvic recurrence decreases by 50%, and 5-year survival improves by 8% to 9%”. Otherwise in Western countries, surgical societies do not suggest to perform LLND in patients without clinically suspected lateral pelvic lymph node metastasis. In Japan lateral pelvic lymph node metastasis is considered to be a localized disease, differently in West this same problem is considered to be a systemic disease associated with a very poor prognosis. For these reasons, in Japan prophylactic LLND is performed in all patients with for Clinical Stage II/III Lower Rectal Cancer for reducing local recurrence and improving survival. In Western countries, lateral pelvic lymph node metastases have been considered a systemic neoplastic spread and for this reason the oncologists treated the lateral pelvic lymph node metastases only by chemoradiation therapy. Other reasons of this behaviour were including the few number of lateral pelvic lymph node metastasis, the negligible survival impact of LLDN over chemoradiation therapy and the high post-operative morbidity associated at LLND. This trial of Fujita represents the high Evidence Basic Medicine milestone in the controversies between East and West in rectal cancer surgery. Nowadays, the neoadjuvant chemo-radiotherapy and the successively TME is the choice treatment for clinical Stage II/III Lower Rectal Cancer in Western countries, the goals are to reduce the risk of cancer recurrence and to shrink the cancer prior to surgery. The role of neoadjuvant chemo-radiotherapy on lateral pelvic lymph node metastasis in advanced low rectal cancer remains unclear. Nowadays, in literature there are few reports about the oncologic outcome of patients with lateral pelvic lymph node metastasis underwent neoadjuvant chemo-radiotherapy. Recently some European societies guidelines suggest the neoadjuvant chemo-radiotherapy and TME with LLND in T3-Ta rectal tumours with involved lateral pelvic lymph node (obturator, internal iliac nodes). The conclusions are the same: lateral pelvic lymph node metastasis cannot be eradicated completely by neoadjuvant chemo-radiotherapy, for these reasons the Authors recommended to perform LLND for the reduction of local recurrence at lateral pelvic lymph node. Fujita et al. included only patients with no clinical evidence of lateral pelvic lymph node enlargement and lateral pelvic lymph nodes less than 10 mm in short-axis diameter as detected on MDCT or MRI were defined as negative nodes; this last choice in the inclusion criteria is very important because the patients enrolled are homogeneous and the risk of local recurrence at lateral pelvic lymph node is the same. Differently, Yamaoka reported a different optimal cut-off value for determining metastasis: 6.0 mm, with a sensitivity of 78.5% and specificity of 82.9% . In effect, Fujita et al. reported that lateral pelvic lymph node metastasis was identified in 26 patients (7.4%) in TME with LLND group, “suggesting that the diagnostic accuracy of clinical lateral pelvic lymph node metastasis might not have been sufficient”. A lot of surgeons researched the factors associated with lateral pelvic lymph node recurrence after TME curative resection of rectal cancer. Actually, Fujita et al. demonstrated the effectiveness of TME with LLDN; but, a new RCT is needed for evaluate the patients underwent neoadjuvant chemo-radiotherapy and TME with or without LLND. The challenge of the new researches is to define the optimal indication for perform LLND and an accurate selection of patients, especially in the case of patients underwent neoadjuvant chemo-radiotherapy.