The incidence and risk factors of low anterior resection syndrome (LARS) after sphincter-preserving surgery of rectal cancer: a systematic review and meta-analysis.

BACKGROUND

Many patients after sphincter-preserving surgery experienced anorectal functional disturbances which were known as low anterior resection syndrome (LARS). Although many studies investigated LARS, there was inconsistency of their assessment tools and results. The aim of this systematic review was to elucidate the incidence and risk factors of LARS by a validated tool-LARS score.

METHODS

A systematic literature search in Pubmed, Embase, and Cochrane Library was conducted in April 2020. Studies investigating patients who were evaluated by LARS score 1 year after their sphincter-preserving surgery due to rectal cancer were included. Meta-analysis of incidence was conducted using the double arcsine method. Meta-analysis of each risk factor was conducted using a random effects model.

RESULTS

A total of 50 studies were included. The pooled incidence of major LARS was 44% (95% CI 40-48%; I = 88%; 36 studies). Long course neoadjuvant radiotherapy (OR 2.89, 95% CI 2.06-4.05; I = 47%; P < 0.01; 10 studies), total mesorectal excision (TME) (OR 2.13, 95% CI 1.49-3.04; I = 53%; P < 0.01; 7 studies), anastomotic leak (OR 1.98, 95% CI 1.34-2.93; I = 39%; P < 0.01; 9 studies), and diverting stoma (OR 1.89, 95% CI 1.58-2.27; I = 0%; P < 0.01; 13 studies) were associated with increased risk of major LARS. No significant difference was found in major LARS incidence between transanal TME and laparoscopic TME (OR 1.36, 95% CI 0.78-2.40; I = 19%; P = 0.28; 4 studies). Pouch reconstruction failed to lower the risk of major LARS in long term (OR 1.43, 95% CI 0.88-2.33; I = 70%; P = 0.29; 9 studies).

CONCLUSION

The incidence of major LARS after sphincter-preserving surgery is relatively high. Neoadjuvant radiotherapy, TME, anastomostic leak, and diverting stoma are major risk factors. No significant differences in postoperative anorectal functions were observed between transanal and laparoscopic TME. Pouch reconstruction was not found to be significantly beneficial to anorectal functions in long term.