Background/Objectives: The improved long-term survival of rectal cancer patients has led to a major increase in the prevalence of functional complications. Understanding which patients are prone to develop major LARS is important for their preoperative counselling and follow-up. Herein, we aimed to assess the risk factors for LARS. Methods: This is a retrospective cohort study on rectal cancer patients. All patient and tumour variables, management plan, type of neoadjuvant therapy, radiation dose to anal sphincter, and perioperative outcomes were collected from the hospital electronic databases. We quantified LARS and compared the score before and after surgery (mean follow-up of 42.2 ± 32 months). Results: A total of 182 patients were included for the final analysis. LARS was present in 43.4% (n = 79) of patients, with 14.8% (n = 27) having minor LARS and 28.5% (n = 52) having major LARS. Age (p = 0.03), male gender (p < 0.00001), smoking (p = 0.04), neoadjuvant radiotherapy (p = 0.02), rectal stump length (p = 0.008), end-to-end anastomosis (p = 0.008), and ileostomy (p = 0.002) were found to significantly increase the rate of LARS. A logistic regression model based on the above variables was able to predict major LARS with good predictive value (AUC 0.700). Conclusions: LARS is highly common after sphincter-preserving surgery, and it is significantly more common in young, male patients with a history of smoking, having mid-lower rectal cancers with neoadjuvant radiotherapy, and undergoing TME surgery with end-to-end low anastomosis and ileostomy.

Background: Low anterior resection syndrome (LARS) is a frequent survivorship problem after sphincter-preserving rectal cancer surgery. Pelvic radiotherapy (RT), often combined with chemotherapy, is frequently implicated in LARS development, but its apparent effect may be confounded by low tumor location and diversion. We evaluated whether RT (±chemotherapy) separates the risk of postoperative LARS severity—especially major LARS—beyond classical anatomic and pathway determinants. Methods: We conducted a single-centre observational cohort study of operated rectal cancer patients managed between 2013 and 2024, who completed the Romanian-validated LARS score by standardized telephone interview after restoration of bowel continuity (up to 18 months postoperatively). Outcomes were postoperative LARS score, LARS category, and major LARS. Comparisons were performed by RT status and by oncologic treatment pattern. Multivariable logistic regression assessed associations with major LARS, adjusting a priori for tumor location and diverting ileostomy; furthermore, extended sensitivity models incorporated technical/pathway variables. Discrimination was explored using 5-fold cross-validated ROC/AUC. Item-level LARS responses were analyzed to characterize symptom phenotype. Results: Overall, 182 patients were included (RT: 106; no RT: 76); 43.4% had LARS (minor 14.8%, major 28.6%). RT-treated patients had higher postoperative LARS scores (median 21 vs. 12; p = 0.002) and a higher prevalence of major LARS (35.8% vs. 18.4%; p = 0.012). Across treatment patterns, LARS severity was highest in RT + chemotherapy. Item-level analyses indicated that RT-associated differences were driven mainly by urgency and clustering domains. In adjusted models, RT was not independently associated with major LARS, whereas low tumor location and diverting ileostomy were strong predictors. Discrimination for major LARS was modest: AUC 0.561 for RT alone, 0.643 for location + ileostomy, and 0.654 for location + ileostomy + RT (5-fold cross-validation). Conclusions: RT is associated with worse unadjusted postoperative bowel dysfunction after rectal cancer surgery and is linked to urgency/clustering-dominant symptom patterns. However, in this cohort, the risk of major LARS was predominantly explained by tumor location and diversion rather than RT alone, supporting integrated risk stratification and early symptom-directed survivorship care.

Background: Low anterior resection syndrome (LARS) is a frequent functional complication after sphincter-preserving rectal cancer surgery. Although tumor location and treatment-related factors are established determinants, the contribution of pelvic skeletal anatomy assessed by magnetic resonance imaging (MRI) pelvimetry remains uncertain. This study evaluated whether three conventional MRI-derived skeletal pelvimetry measurements provide incremental predictive information for major LARS beyond a parsimonious preoperative clinical reference model. Methods: This single-center observational cohort study included 168 patients who underwent sphincter-preserving rectal cancer surgery and completed postoperative LARS assessment. MRI pelvimetry included anteroposterior pelvic diameter, interspinous distance, and sacral curvature depth. Associations with LARS score and major LARS were evaluated using correlation analyses, pelvic-tertile comparisons, and multivariable logistic regression. Firth penalized logistic regression was prespecified as a sensitivity analysis. The primary clinical reference model included age, categorical tumor position, and neoadjuvant radiotherapy. Internal validation used stratified five-fold cross-validation repeated 100 times. Incremental model fit was assessed using a likelihood-ratio test. Results: Major LARS occurred in 48 patients (28.6%), and the median postoperative LARS score was 18 (interquartile range 9–31). LARS scores and major LARS prevalence were similar across anteroposterior pelvic diameter tertiles. In the parsimonious multivariable model, low tumor position was associated with major LARS (OR 9.51, 95% CI 2.00–45.15; p = 0.005), whereas anteroposterior pelvic diameter and interspinous distance were not associated with major LARS. The parsimonious preoperative clinical model achieved a mean repeated five-fold cross-validated AUC of 0.669, compared with 0.671 after addition of MRI pelvimetry (ΔAUC = +0.002, 95% CI −0.052 to 0.054), with no statistically detectable improvement in nested-model fit (likelihood-ratio p = 0.122). Brier scores were 0.187 for both models. Calibration, overall prediction error, and decision-curve performance were similar between models. Conclusions: In this selected retrospective cohort, the three conventional MRI-derived skeletal pelvimetry measurements evaluated did not demonstrate a clear incremental improvement in prediction of major LARS beyond the parsimonious preoperative clinical reference model.