Inferior mesenteric artery ligation level in rectal cancer surgery: still no answer-a systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review and meta-analysis is to summarize the current scientific evidence regarding the impact of the level of inferior mesenteric artery (IMA) ligation on post-operative and oncological outcomes in rectal cancer surgery.

METHODS

We conducted a systematic review of the literature up to 06 September 2022. Included were RCTs that compared patients who underwent high (HL) vs. anterior (LL) IMA ligation for resection of rectal cancer. The literature search was performed on Medline/PubMed, Scopus, and the Web of Science without any language restrictions. The primary endpoint was overall anastomotic leakage (AL). Secondary endpoints were oncological outcomes, intraoperative complications, urogenital functional outcomes, and length of hospital stay.

RESULTS

Eleven RCTs (1331 patients) were included. The overall rate of AL was lower in the LL group, but the difference was not statistically significant (RR 1.43, 95% CI 0.95 to 2.96). The overall number of harvested lymph nodes was higher in the LL group, but the difference was not statistically significant (MD 0.93, 95% CI - 2.21 to 0.34). The number of lymph nodes harvested was assessed in 256 patients, and all had a laparoscopic procedure. The number of lymph nodes was higher when LL was associated with lymphadenectomy of the vascular root than when IMA was ligated at its origin, but there the difference was not statistically significant (MD - 0.37, 95% CI - 1.00 to 0.26). Overall survival at 5 years was slightly better in the LL group, but the difference was not statistically significant (RR 0.98, 95% CI 0.93 to 1.05). Disease-free survival at 5 years was higher in the LL group, but the difference was not statistically significant (RR 0.97, 95% CI 0.89 to 1.04).

CONCLUSIONS

There is no evidence to support HL or LL according to results in terms of AL or oncologic outcome. Moreover, there is not enough evidence to determine the impact of the level of IMA ligation on functional outcomes. The level of IMA ligation should be chosen case by case based on expected functional and oncological outcomes.

5 year oncological outcomes of the HIGHLOW randomized clinical trial

INTRODUCTION

The oncological outcomes of low ligation (LL) compared to high ligation (HL) of the inferior mesenteric artery (IMA) during low-anterior rectal resection (LAR) with total mesorectal excision are still debated. The aim of this study is to report the 5 year oncologic outcomes of patients undergoing laparoscopic LAR with either HL vs. LL of the IMA MATERIALS AND METHODS: Between June 2014 and December 2016, patients who underwent elective laparoscopic LAR + TME in 6 Italian non-academic hospitals were randomized to HL or LL of IMA after meeting the inclusion criteria (HighLow trial; ClinicalTrials.gov Identifier NCT02153801). We analyzed the rate of local recurrence, distant metastasis, overall survival, disease-specific survival, and disease-free survival at 5 years of patients previously enrolled.

RESULTS

Five-year follow up data were available for 196 patients. Recurrence happened in 42 (21.4%) of patients. There was no statistically significant difference in the distant recurrence rate (15.8% HL vs. 18.9% LL; P = 0.970) and pelvic recurrence rate (4,9% HL vs 3,2% LL; P = 0.843). No statistically significant difference was found in 5-year OS (p = 0.545), DSS (p = 0.732) or DFS (p = 0.985) between HL and LL. Low vs medium and upper rectum site of tumor, conversion rate, Clavien-Dindo post-operative grade ≥3 complications and tumor stage were found statistically significantly associated to poor oncological outcomes in univariate analysis; in multivariate analysis, however, only conversion rate and stage 3 cancer were found to be independent risk factors for poor DFS at 5 years.

CONCLUSION

We confirmed the results found in the previous 3-year survival analysis, the level of inferior mesenteric artery ligation does not affect OS, DSS and DFS at 5-year follow-up.