Lateral lymph node involvement presents another challenge in rectum cancer in the age of neoadjuvant chemoradiotherapy + total mesorectal excision: an evaluation of survival outcomes

Purpose In the last decades, total mesorectal excision (TME) and neoadjuvant chemoradiotherapy (nCRT) have produced an undeniable improvement in the treatment of rectal cancer. However, local recurrence is still an important problem, and the effect of lateral lymph node (LLN) involvement on local recurrence is a controversial issue. The aim of this study was to investigate the effects of LLN status on local recurrence and survival in rectal cancers treated with nCRT + TME. Methods Clinical features, pre- and post-nCRT lateral pelvic region imaging, long-term local recurrence, and the survival outcomes of 114 patients who underwent nCRT + TME for rectal cancer were evaluated. Results On MRI before nCRT, 20 (17.5%) patients had lateral lymph nodes (LLN+), and 94 (82.5%) patients had no lymph nodes in the lateral pelvic compartments (LLN−). Local recurrences at 1 year in LLN+ and LLN− patients were 3 (15.8%) and 2 (2.3%), respectively ( p =0.039). Five-year local recurrence-free survival rates and the mean duration of recurrence-free survival in LLN+ and LLN− patients were 56.2%, 42.6 months, and 87.3% 66.9 months, respectively ( p =0.001). Disease-free survival and overall survival were shorter in LLN+ patients, but the difference was not statistically significant ( p =0.096 and p =0.46, respectively). In the multivariate analysis, LLN involvement was determined to be an independent risk factor for local recurrence-free survival (Hazard Ratio 4.54, p =0.003). Conclusion Lateral lymph node involvement causes local recurrence to remain high after nCRT + TME. LLN status should be considered in treatment planning. Further studies are needed to define precise criteria for LLN involvement and the effect of LLND on local recurrence and survival.