Purpose/Objective(s): A prospective phase II trial was introduced in a single Southeast Asian tertiary oncology centre to evaluate Linac-based VMAT Stereotactic Body Radiotherapy for prostate cancer. The purpose of this study is to report on toxicity and quality of life parameters following treatment.
Materials/Methods: From 2014 – 2016, 37 patients with National Comprehensive Cancer Network Low or a single Intermediate risk factor (defined as T2b-c, PSA 10-20 or Gleason score 7), histologically proven organ-confined prostate adenocarcinoma were treated with Linac-based VMAT SBRT. 36.25Gy in five fractions was delivered on alternate days to the prostate, with inclusion of the base of the seminal vesicles in intermediate risk patients. No hormonal therapy was used. Toxicity and Health Related Quality of Life were assessed using CTCAE 4.0 and the EPIC questionnaire up to 2 years after treatment.
Results: 32 patients with more than 3 months follow-up were included in the analysis. Median duration of follow-up was 21 months (range 3-30 months) and median age was 68 years (range 54-78 years). Acute toxicities peaked at 1 week post SBRT with 8.82% Grade 1 and 8.82% Grade 2 Gastrointestinal, and 67.67% Grade 1 and 14.71% Grade 2 genitourinary. All Grade 2 toxicities resolved to Grade 1 or less at 1-month post-SBRT. There was no Grade 3 and above toxicity. Late gastrointestinal toxicity was restricted to Grade 1 only. Three patients (9.4%) had grade 2 late urinary toxicity in the form of poor flow requiring alpha-blockers, which could all be subsequently weaned down. Mean EPIC scores measured at baseline, 1 year and 2 years were stable in the Urinary, Gastrointestinal and Hormonal domains. In the sexual domain, mean 1st year score (49.23) held steady from baseline (51.25) but deteriorated significantly by the 2ndyear (39.90). At one and two years, 73.6% and 81.8% respectively of patients were either 'satisfied or extremely satisfied' with the treatment received.
Conclusion: Linac-based VMAT SBRT delivered on alternate days is well tolerated by Asian patients with low/low-intermediate risk prostate cancer with a sanguine toxicity profile and minimal impact on quality of life.