Acute and late toxicity in prostate cancer patients treated with moderately vs ultra-hypofractionated radiotherapy

Introduction: Prostate cancer is the most frequently diagnosed male malignancy in Colombia. While modern radiotherapy techniques allow for hypofractionated schedules due to the low alpha/beta ratio of prostate adenocarcinoma, real-world comparative data between moderate and ultra-hypofractionation in Latin American settings remain limited. Objective: To compare acute and early late toxicity in patients with prostate cancer treated with moderately hypofractionated radiotherapy versus those treated with ultra-hypofractionated regimen. Methods: A comparative historical cohort study was conducted at a Colombian oncology center between 2018 and 2025. A total of 229 patients with non-metastatic prostate cancer (T1-T4) were enrolled (MHRT: n=143; UHRT: n=86). Toxicity was graded using CTCAE criteria. Multivariable logistic regression was used to identify independent predictors of toxicity. Results: Acute toxicity was significantly higher in the MHRT group compared to the UHRT group (25.17% vs. 11.63%; p=0.013). Similarly, late toxicity was more frequent in the MHRT group (37.06% vs. 9.30%; p<0.001), with erectile dysfunction as the most common late event. Multivariable analysis showed that UHRT was independently associated with lower odds of acute toxicity (aOR 0.44; 95% CI 0.19-0.99; p=0.048). Conclusion: UHRT showed a generally favorable safety profile, with trends toward lower acute and late toxicity compared to MHRT. In middle-income settings such as Colombia, UHRT may offer a practical approach to enhance treatment efficiency and patient access, while maintaining acceptable clinical outcomes.