Significance, diagnosis and treatment of lateral lymph nodes in rectal cancer : A systematic review

Introduction: Patients with low rectal cancer are at risk for lateral lymph node metastasis (LLNM). Neoadjuvant chemoradiotherapy (CRT) is used to eradicate LLNM in the West, whereas in Japan the addition of lateral lymph node dissection (LLND) to total mesorectal excision (TME) is performed. A systematic review was conducted to assess incidence, location, risk factors and diagnosis of LLNM and lateral lymph node (LLN) treatment outcomes. Method: The Medline, Embase and Cochrane databases were searched for English-language articles pertaining to LLNs in rectal cancer. Results: 242 studies were identified and 15 prospective studies selected for qualitative analysis. LLNM was detected in 7–40% of patients who underwent LLND, and lower incidence occurred in patients without preoperative suspicion of LLNM. LLNs located along the middle rectal artery were most common. LLNM was associated with female sex, advanced T stage and positive mesorectal nodes. LLN short-axis diameter of ≥10 mm on preoperative imaging appeared to predict LLNM after neoadjuvant CRT. The addition of LLND to TME seemed to decrease LR and improve survival rates, with comparable results seen for CRT. LLND appeared to be associated with longer operation time, greater blood loss and increased risk of sexual and urinary dysfunction. Conclusion: LLND could be advantageous for patients with suspected LLNM, but associated morbidities need to be considered. Further studies are needed to improve preoperative identification of LLNs and to determine how to manage persistent enlarged LLNs after CRT. Furthermore, the applicability of LLND in a Western population needs to be investigated