Aim: The aim of this study is to evaluate whether the duration of external beam radiotherapy (RT) influences treatment outcomes in prostate cancer patients. Materials and methods: 80 men with prostate cancer were treated with definitive radiotherapy (RT). Some intermediate- and high-risk patients did not receive androgen deprivation therapy due to physician or patient preference and timing related to clinical trial publications. Treatment interruptions were measured using the nontreatment day ratio (NTDR). Follow-up evaluations were based on prior institutional treatment protocols. Data analysis was done using SSPS software.Data analysis was done using SSPS software.Cox proportional hazards regression analysis was used for univariate and multivariate analyses. Results: A total of 80 patients were included in the study, with a median age of 55 years. The Gleason score distribution showed that 70% of patients had scores between 2–6, 20% had a score of 7, and 10% had scores between 8–10. Pretreatment PSA levels had a median value of 8.6 ng/mL, with 65% of patients having PSA ≤10 ng/mL, 20% having PSA between >10–19.99 ng/mL, and 15% having PSA ≥20 ng/mL. Regarding tumor stage, 57.5% of patients were classified as T1, 22.5% as T2, and 20% as T3. Risk stratification revealed that 52.5% of patients were in the low-risk category, 15% in the intermediate-risk category, and 32.5% in the high-risk group. Conclusion: Longer treatment duration was found to negatively impact low-risk patients.