Linear Accelerator-Based Stereotactic Body Radiotherapy of 36.25 Gy in Five Fractions for Localised Prostate Cancer: A Retrospective Single-Institution Cohort Study.

Abstract

Background: Stereotactic body radiotherapy has become an established treatment option for localised prostate cancer. However, real-world evidence from routine clinical practice remains limited, particularly in cohorts that include older patients. We therefore report long-term outcomes and treatment-related adverse events after a uniform linear accelerator-based stereotactic body radiotherapy regimen.

Methods: We retrospectively reviewed consecutive patients with localised prostate adenocarcinoma treated between May 2016 and June 2020 with definitive stereotactic body radiotherapy of 36.25 Gy in five fractions delivered every other day. Risk stratification followed National Comprehensive Cancer Network criteria.

Results: A total of 232 patients were included. The median age was 73 years (range, 52-88), and the median follow-up was 84.5 months (range, 3.6-113.8). Overall survival at 3, 5, and 7 years was 98.2%, 95.1%, and 93.3%, respectively. Biochemical recurrence-free survival at 3, 5, and 7 years was 95.9%, 90.2%, and 87.8%, respectively. In patients with higher-risk disease, biochemical recurrence-free survival at 5 years was 90.9% in the high-risk group and 74.2% in the very high-risk group. No Grade 3 acute gastrointestinal or genitourinary events occurred. Late Grade 3 genitourinary adverse events occurred in 5 patients (2.2%) and late Grade 3 gastrointestinal adverse events in 3 patients (1.3%); no Grade 4 or 5 treatment-related adverse events were observed.

Conclusions: In this single-institution real-world cohort, linear accelerator-based stereotactic body radiotherapy was associated with long-term disease control and a limited incidence of severe late adverse events. These findings support implementation of five-fraction prostate stereotactic body radiotherapy in routine practice with appropriate patient counselling and long-term surveillance.