Association Between Baseline Neutrophil-to-Lymphocyte Ratio and Short-Term Urinary Quality of Life During BCG Induction in Male Patients with Non-Muscle-Invasive Bladder Cancer: A Prospective Observational Study

<b>Background/Objectives:</b> Intravesical Bacillus Calmette-Guérin (BCG) is the standard adjuvant treatment for high-risk non-muscle-invasive bladder cancer (NMIBC), but treatment-related urinary toxicity may compromise quality of life (QoL) and adherence. The neutrophil-to-lymphocyte ratio (NLR), a marker of systemic inflammation, has been linked to oncologic outcomes in bladder cancer, but its association with urinary symptom burden during BCG therapy remains unclear. We aimed to assess whether baseline NLR is associated with early deterioration in urinary symptoms and urinary QoL following BCG induction. <b>Methods:</b> This prospective study included male patients with NMIBC treated with intravesical BCG. Baseline demographics, comorbidities, laboratory parameters, and urinary symptoms were recorded. Patients were stratified into two groups according to baseline NLR (<3 vs. ≥3). Urinary outcomes were assessed at baseline and 8 weeks using the International Prostate Symptom Score (IPSS) and the IPSS-related QoL item. Univariable and multivariable linear regression analyses were performed. <b>Results:</b> A total of 96 patients were analyzed. Median baseline NLR was 2.6 (IQR: 2.1-3.8). Patients with NLR ≥ 3 (<i>n</i> = 34) and NLR < 3 (<i>n</i> = 62) had comparable baseline characteristics and urinary scores. At 8 weeks, patients with NLR ≥ 3 experienced a greater worsening of urinary symptoms (median IPSS 24 vs. 21, <i>p</i> = 0.02; median change +5 vs. +2, <i>p</i> = 0.01) and QoL (median 5 vs. 4, <i>p</i> = 0.03). Univariable regression confirmed the association of NLR ≥ 3 with worse QoL (β = +0.74; <i>p</i> = 0.003) and higher IPSS (β = +2.20; <i>p</i> = 0.021). Modeled as a continuous variable, each one-unit increase in NLR corresponded to a +0.20 worsening in QoL (<i>p</i> = 0.008). In the multivariable analyses adjusted for baseline IPSS and concomitant CIS, NLR remained independently associated with QoL decline. <b>Conclusions:</b> Baseline NLR was independently associated with worsening urinary symptoms and QoL during BCG induction in NMIBC patients. NLR may represent a simple and accessible biomarker for early risk stratification during BCG induction, warranting validation in larger, longer-term prospective trials.