# Understanding risk factors for low anterior resection syndrome in a South American cohort

## TL;DR

This study identifies younger age and preoperative radiotherapy as risk factors for severe bowel dysfunction after rectal cancer surgery in Chile.

## Contribution

The study provides new insights into LARS risk factors specific to a South American population, emphasizing preoperative radiotherapy and younger age as independent predictors.

## Key findings

- Nearly half of patients developed LARS, with 29.1% classified as major.
- Younger age and preoperative radiotherapy were independent predictors of severe LARS.
- Total mesorectal excision and protective ileostomy were associated with LARS severity but not statistically significant in multivariate analysis.

## Abstract

Low Anterior Resection Syndrome (LARS) is a common postoperative bowel dysfunction in patients undergoing sphincter-preserving surgery for rectal cancer. Symptoms include fecal and gas incontinence, urgency, increased bowel frequency, and fragmented evacuations. LARS significantly impairs quality of life, affecting up to 90% of patients. Various factors contribute to its development, such as tumor height, extent of mesorectal excision, preoperative radiotherapy, and ileostomy. However, these factors are less studied in South American populations, where racial, cultural, and healthcare system differences may influence outcomes.

The aim of the study was to evaluate risk factors associated with LARS in a Chilean cohort of rectal cancer patients, with emphasis on cases classified as severe.

A non-concurrent prospective cohort study including patients who underwent low anterior resection between 2012 and 2021. Perioperative data collected included tumor height, surgical procedure type, preoperative radiotherapy, and protective ileostomy. Univariate and multivariate analyses were conducted to identify factors significantly associated with severe LARS, using the LARS score adapted to Chilean Spanish.

A total of 110 patients were included, with a median follow-up of 51 months. LARS was identified in 52.7% of cases, with 29.1% classified as major. Younger age, lower tumors, total mesorectal excision, preoperative radiotherapy, and ileostomy were significantly associated with severe LARS in univariate analysis. In multivariate analysis, only younger age and preoperative radiotherapy remained as independent risk factors.

In this Chilean cohort, nearly half of patients undergoing sphincterpreserving surgery for rectal cancer developed LARS. About one-third had the severe form, highlighting the need for targeted strategies to mitigate LARS and improve patient quality of life.

LARS significantly impairs quality of life, highlighting the need for personalized perioperative strategies.

Nearly half of patients developed LARS, with 29.1% classified as major LARS after rectal cancer surgery.

Preoperative radiotherapy and younger age were independent predictors of severe LARS.

Low Anterior Resection Syndrome (LARS) is a recognized complication following sphincter-sparing rectal cancer surgery and is associated with considerable impairment in bowel function. The symptoms vary widely among patients and may include fecal and gas incontinence, urgency, increased frequency of defecation, and stool clustering. Such disturbances can lead to relevant limitations in daily activities, with up to 90% of patients reporting a significant impact on their quality of life (QoL). The pathophysiology of LARS is multifactorial, with several key risk factors contributing to its development.

This study underscores the significant burden of Low Anterior Resection Syndrome (LARS) among Chilean patients undergoing sphincter-sparing rectal cancer surgery, with half of them experiencing some degree of LARS and nearly one-third classified as having major LARS. Among the evaluated risk factors, preoperative radiotherapy and younger age emerged as independent predictors of major LARS, while total mesorectal excision and protective ileostomy were also associated with increased severity, though they did not reach statistical significance in the multivariate analysis. These findings emphasize the critical role of comprehensive preoperative counseling and multidisciplinary decision-making in mitigating LARS risk and optimizing long-term functional outcomes in rectal cancer patients.