[Evaluation of lateral lymph node metastasis in mid-low rectal cancer and planning of multi-disciplinary treatment]

After the implementation of neoadjuvant chemoradiotherapy and total mesorectal excision, lateral local recurrence becomes the major type of local recurrence after surgery in rectal cancer. Most lateral recurrence develops from enlarged lateral lymph nodes on an initial imaging study. Evidence is accumulating to support the combined use of neoadjuvant chemoradiotherapy and lateral lymph node dissection. The accuracy of diagnosing lateral lymph node metastasis remains poor. The size of lateral lymph nodes is still the most commonly used variable with the most consistent accuracy and the cut-off value ranging from 5 to 8 mm on short axis. The morphological features, differentiation of the primary tumor, circumferential margin, extramural venous invasion, and response to chemoradiotherapy are among other risk factors to predict lateral lymph node metastasis. Planning multiple disciplinary treatment strategies for patients with suspected nodes must consider both the risk of local recurrence and distant metastasis. Total neoadjuvant chemoradiotherapy is the most promising regimen for patients with a high risk of recurrence. Simultaneous Integrated Boost Intensity-Modulated Radiation Therapy seemingly improves the local control of positive lateral nodes. However, its impact on the safety of surgery in patients with no response to the treatment or regrowth of lateral nodes remains unclear. For patients with smaller nodes below the cut-off value or shrunken nodes after treatment, a close follow-up strategy must be performed to detect the recurrence early and perform a salvage surgery. For patients with stratified lateral lymph node metastasis risks, plans containing different multiple disciplinary treatments must be carefully designed for long-term survival and better quality of life.