Association Between Low Anterior Resection Syndrome and Lower Urinary Tract Symptom Severity After Restorative Rectal Cancer Surgery

Background: Low anterior resection syndrome (LARS) and lower urinary tract symptoms (LUTS) are common after restorative rectal cancer surgery, but whether their postoperative severity is associated after accounting for relevant clinical, anatomical, and treatment-related factors remains unclear. Methods: We conducted a retrospective, single-centre cohort study of patients treated for rectal cancer at the Regional Institute of Oncology, Iași, Romania, between 2013 and 2024. Patients were eligible if they underwent sphincter-preserving rectal resection, achieved restoration of bowel continuity, and completed the LARS score and International Prostate Symptom Score (IPSS) during the same postoperative telephone assessment. The primary analysis used proportional-odds ordinal logistic regression to evaluate the association between LARS and IPSS categories after adjustment for neoadjuvant radiotherapy, chemotherapy, extent of mesorectal excision, MRI-measured distance from the tumour to the anal verge, age, sex, body mass index, diabetes, and smoking. Multiple sensitivity and model-diagnostic analyses were performed to assess the robustness of the primary association. Results: Of 404 patients managed during the study period, 190 were included in the analytic cohort. Major LARS was present in 53 patients (27.9%), and moderate-to-severe LUTS in 84 (44.2%). LARS score and IPSS were modestly correlated (Pearson r = 0.225, p = 0.0018; Spearman ρ = 0.237, p = 0.0010). Moderate-to-severe LUTS occurred in 31 of 53 patients with major LARS (58.5%) and in 53 of 137 with no or minor LARS (38.7%; p = 0.021). In the primary adjusted model, each one-category increase in LARS severity was associated with greater IPSS severity (OR 1.75, 95% CI 1.25–2.46, p = 0.0012), and addition of LARS significantly improved model fit (likelihood-ratio χ2 = 10.85, p = 0.0010). Major LARS was associated with approximately threefold higher odds of greater IPSS severity compared with no LARS (OR 3.05, 95% CI 1.54–6.04, p = 0.0014). Diabetes was also associated with greater IPSS severity after multivariable adjustment (OR 3.32, 95% CI 1.44–7.67, p = 0.0049). Results remained materially unchanged across sensitivity analyses. Item-level correlations were weak, and none remained significant after Bonferroni correction. Conclusions: Greater postoperative LARS severity was associated with greater contemporaneously measured LUTS severity after multivariable adjustment. This association was consistent across multiple correlated sensitivity analyses but does not establish temporal direction or a shared causal mechanism. Patients with major LARS may therefore warrant concurrent assessment for urinary symptoms during postoperative and survivorship follow-up.