Résumé : Background: Lower urinary tract symptoms (LUTSs) may develop in men with prostate cancer (PCa) and can impact quality of life (QoL). Gonadotropin-releasing hormone (GnRH) agonists as androgen deprivation therapy are standard treatment for PCa, however, data are limited on their effects on LUTSs. A grouped analysis of national observational, non-interventional studies initiated in clinical practice was performed to assess the effectiveness of triptorelin in reducing moderate or severe LUTSs, measured using the International Prostate Symptom Score (IPSS) in men with advanced or metastatic PCa. Methods: Men with PCa and LUTSs scheduled to receive triptorelin (3-month or 1-month extended release formulation) were recruited into prospective, non-interventional studies at centres in Algeria, Australia, Belgium, China, Hungary, Romania and South Korea. The primary effectiveness endpoint was the proportion of patients with moderate or severe LUTSs, assessed by IPSS, after 48 weeks. Secondary endpoints included: total IPSS, QoL due to urinary symptoms (IPSS Question 8) and prostate-specific antigen (PSA) levels at 24 and 48 weeks. Results: A total of 2701 patients were recruited; 1851 patients with moderate or severe LUTSs at baseline (IPSS > 7), received triptorelin and had follow-up IPSS (efficacy population). The proportion of patients with moderate or severe LUTSs was reduced to 67.2% from baseline at week 48, following a reduction to 75.9% at week 24: the overall time effect was significant (p < 0.001). QoL due to urinary symptoms significantly improved from a mean score of 3.7 at baseline, to adjusted means of 2.5 and 2.1, at weeks 24 and 48, respectively (p < 0.001 versus baseline). Mean PSA levels were reduced from 158.8 ng/ml at baseline to 11.5 and 16.0 ng/ml at weeks 24 and 48, respectively. Conclusions: Within the limitations of these observational studies, improvements in LUTSs and QoL observed after 24 weeks and maintained at 48 weeks indicate that triptorelin-induced effects improve LUTSs in patients with advanced PCa.