Ultrahypofractionated Proton Radiation Therapy in the Treatment of Low and Intermediate-Risk Prostate Cancer-5-Year Outcomes
Abstract
PURPOSE: To analyse the 5-year biochemical disease free survival (bDFS) and late toxicity profile in patients with prostate cancer treated with pencil beam scanning (PBS) proton radiotherapy. MATERIAL AND METHODS: Between January 2013 and March 2016, 284 prostate cancer patients were treated utilising IMPT (Intensity Modulated Proton Therapy), with an ultra-hypofractionated schedule (36.25 GyE/5 fractions).
Five patients were immediately lost from follow-up and thus were excluded from analysis. Data for 279 patients were prospectively collected and analysed with a median follow-up time of 56,5 (range 3.4 - 87.5) months.
The mean age at time of treatment was 64.5 (40.1-85.7) years, median PSA value was 6.35 μg/l (0.67-17.3 μg/l). 121 (43.4%) patients had low risk, 125 pts (44.8%) had favorable and 33 (11.8%) unfavorable intermediate risk cancer. 49 (17.6%) patients underwent neoadjuvant hormonal therapy, no patients had adjuvant hormonal therapy. bDFS and late toxicity profiles were evaluated. RESULTS: The median treatment time was 9 days (range 7-18 days).
The 5-year bDFS was 96.9%, 91.7 and 83.5% for the low-, favorable and unfavorable intermediate-risk group, respectively. Late toxicity (CTCAE-v.4) was: Gastrointestinal (GI): G1-62 patients (22%), G2-20 (7.2%), G3-1 (0.36%); Genitourinary (GU): G1-80 (28.7%), G2-14 (5%), no G3 toxicity was observed.
PSA relapse was observed in 17 patients (6.1%), lymph node or bone recurrence was detected in 11 patients. Four (1.4%) local recurrences were detected.
Nine (3.2%) died from causes unrelated to prostate cancer. No deaths related to prostate cancer were reported.
CONCLUSION: Ultra-hypofractionated proton beam radiotherapy for prostate cancer is effective with long term bDFS comparable with other fractionation schedules and with minimal serious long-term GI and GU toxicity.