Moderately Hypofractionated Versus Conventionally Fractionated Volumetric Modulated Arc Therapy for Definitive Treatment of Localised Prostate Cancer

Introduction: This retrospective study compares the treatment outcome of a reduced dose with moderate hypofractionation (60 Gray in 20 fractions [60 Gy/20 fr]) with conventionally fractionated (76 Gy/38 fr) volumetric modulated arc therapy for definitive treatment of localised prostate cancer in a public hospital in Hong Kong.Methods: All patients with low-or intermediate-risk prostate cancer (defined according to the National Comprehensive Cancer Network Guidelines) who received definitive radiotherapy from 1 January 2017 to 30 June 2022 were included.Results: A total of 105 patients were identified (58 receiving moderate hypofractionation and 47 receiving conventional fractionation).The median follow-up period was 38.3 months.Grade 2 acute gastrointestinal (GI) toxicity was more common with moderate hypofractionation than with conventional fractionation (15.5% vs. 2.1%, 95% confidence interval = 1.03-69.33;p = 0.02).In the moderate hypofractionation cohort, the planning target volume (PTV) in patients who experienced grade ≥2 acute genitourinary (GU) toxicity was significantly higher than those who did not (p = 0.03).None of the patients developed grade ≥3 acute GI toxicity.The incidence of grade 3 acute or late GU and late GI toxicities was rare with both fractionation schedules. Conclusion:This study shows that moderately hypofractionated radiotherapy is a safe, effective and feasible alternative to conventionally fractionated radiotherapy for low-and intermediate-risk prostate cancer in the Chinese community.Patients should be counselled on the potential increase in low-grade acute GI toxicity with moderate hypofractionation, which is usually self-limited and is not associated with increases in long-term toxicity.Close monitoring for acute GU toxicity in patients with larger PTVs is warranted.