A meta-analysis of the prevalence of low anterior resection syndrome and systemic review of risk factors

Background: With the increasing use of low anterior resection (LAR) to treat rectal cancer and avoid a permanent stoma, there has been increasing recognition of mid/long term post-operative persisting altered bowel function known as Low Anterior Resection Syndrome (LARS). The aim of this review is to estimate the prevalence of LARS, using studies which utilise the LARS score as their data collection tool. Factors implicated in the causation of the syndrome will also be investigated as it will together allow for better informed consent for patients undergoing treatment. Methods: A systematic literature search was conducted using Pubmed, Ovid Medline and the Cochrane database. Searches were performed using a combination of MeSH (medical subject headings) terms and key terms. Results: The estimated prevalence of major LARS ranged from 17.8% - 56%, with a mean of 31.5%. The patient population who has undergone a LAR is heterogenous with much variability due to tumour, patient and treatment characteristics. Radiotherapy and tumour height were the most consistently assessed variables and reached statistical significance in 8 and 7 of the studies respectively, both showing a consistent negative effect on bowel function. Defunctioning ileostomy was found to have a statistically significant negative impact on bowel function in 4 studies. Conclusions: There is likely a significant prevalence of mid-term persisting LARS after LAR. Larger studies that have greater patient numbers and more robust study design suggest that overall prevalence is between 40-52%. Radiotherapy, whether pre or post-operative, and low tumour height are the 2 factors which have the greatest negative impact of patients bowel function following LAR