Metastatic lymph node ratio as a prognostic factor after laparoscopic total mesorectal excision for extraperitoneal rectal cancer
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The lymph node ratio (LNR; number of positive nodes divided by total nodes harvested) has been demonstrated to be a prognostic factor in colon cancer, but its role in extraperitoneal rectal cancer is still debated; furthermore, no data are available on laparoscopic rectal resection. The aim of this study was to evaluate the prognostic impact of LNR on long-term outcomes after laparoscopic total mesorectal excision (LTME) for extraperitoneal cancer in consecutive patients with a 5-year minimum follow-up.
This study is a prospective analysis of consecutive patients who underwent LTME for adenocarcinoma of the extraperitoneal rectum.
LTME was performed in 158 patients. The median number of LN harvested was 12 (range = 3–25). The proportion of specimens with fewer than 12 examined LN was significantly higher in patients who had neoadjuvant chemoradiotherapy (p < 0.001). During a median follow-up period of 122 months, the local recurrence rate was 8 %. At univariate analysis, disease-free survival and overall survival significantly decreased with increasing LNR (p < 0.001). Multivariate analysis showed that the distal margin ≤1 cm was the only independent predictor of local recurrence (p = 0.028). LNR (cutoff value = 0.25) and lymphovascular invasion were significant prognostic factors for both disease-free (p = 0.015 and p = 0.046, respectively) and overall survival (p = 0.031 and p = 0.040, respectively). Even in the subgroup of patients in whom fewer than 12 LN were examined, LNR confirmed its prognostic role, with a statistical trend toward worse disease-free survival and overall survival.
Metastatic LNR is an independent prognostic factor for disease-free survival and overall survival after LTME for extraperitoneal rectal cancer.
KeywordsLymph node ratio Survival Laparoscopy Total mesorectal excision Rectal cancer
No funds, grants or support was received to complete the study.
Marco Ettore Allaix, Alberto Arezzo, Paola Cassoni, Massimiliano Mistrangelo, Giuseppe Giraudo, and Mario Morino have no conflicts of interest or financial ties to disclose.
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