Metastatic lymph node ratio as a prognostic factor after laparoscopic total mesorectal excision for extraperitoneal rectal cancer

Abstract

BackgroundThe 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. Methods This study is a prospective analysis of consecutive patients who underwent LTME for adenocarcinoma of the extraperitoneal rectum. Results 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. Conclusion Metastatic LNR is an independent prognostic factor for disease-free survival and overall survival after LTME for extraperitoneal rectal cancer. Keywords Lymph node ratio Survival Laparoscopy Total mesorectal excision Rectal cancer Excellence of surgical technique is of particular relevance in the treatment of extraperitoneal rectal cancer. Routine excision of the intact mesorectum during resection of cancer of the middle and lower rectum has resulted in a significant decrease in local recurrence rates [1]. Developed and popularized by Heald and co worker [1], total mesorectal excision (TME) is presently the surgical gold standard, with a 4 % local recurrence rate and a 78 % tumor-free survival rate in curative cases at 5 years [2]. A recent meta-analysis by Huang et al. [3] of randomized controlled trials that included small numbers of patients with upper or mid-to-low rectal cancer did not show differences between laparoscopic and open surgery in terms of the number of lymph nodes (LN) harvested, local recurrence, 3-year disease-free survival, and overall survival. Although a minimum of 12 LN in the

The lymph node ratio does not provide additional prognostic information compared with the N1/N2 classification in Stage III colon cancer

“… first applied the LNR concept to the outcome of colorectal cancer in 2005. Several subsequent studies have established that the LNR is predictive of outcome , but it has not been established whether the LNR is superior to N1/N2 staging. Wang et al .…”

Prognostic value of lymph node ratio in patients with pathological N1 non-small cell lung cancer: a systematic review with meta-analysis

“…The TNM NSCLC staging system currently uses only the anatomic location of LNs to define N status. The LNR has been shown to be an important prognostic factor in several malignancies (13)(14)(15)(16)(17)(18)(19) and may overcome the limitation in the number of LNs sampled. Consistent with this notion Bria et al showed an association between the LNR and lung cancer outcomes (12).…”

“…Therefore, the prognostic accuracy of the actual number of positive LNs is potentially restricted (12). The lymph node ratio (LNR)-the number of positive LNs divided by the number of LNs examined-has been suggested to be a more accurate prognostic indicator than the number of LNs with metastasis in different types of cancer including thyroid, gastric, colorectal, and cancer (13)(14)(15)(16)(17)(18)(19).…”

Prognostic Impact of Lymph Node Ratio in Obstructive Colorectal Cancer

“…LNR is defined as the number of positive lymph nodes identified divided by the total lymph nodes examined. Lower LNR indicates a better prognosis with a higher overall and disease-free survival [5,7,8]. Some studies have shown LNR to Citation: Jacquelyn Turner, Lampros Liasis, George Malietzis, Ayana Chase, E. Shyam P. Reddy, et al (2017) Prognostic Impact of Lymph Node Ratio in Obstructive Colorectal Cancer.…”