HYPOFRACTIONATED RADIOTHERAPY TO THE PROSTATE BED WITH INTENSITY MODULATED RADIATION THERAPY (IMRT): A PHASE II STUDY

Introduction: Prostate cancer (Pca) management can include radical prostatectomy (RP) plus or minus radiotherapy (RT). Post-operative, radiotherapy is prescribed in the adjuvant setting or in case of biochemical failure (salvage treatment). Historically, RT is delivered using conventional doses (1.82 Gy /day), to a total of 647OGy to the prostate surgical bed. Hypofractionated RT has been demonstrated to be safe and effective in the treatment of intact Pca, but RT use in the post-operative setting lack of high-quality evidence. The current study aims to evaluate the safety and effectiveness of hipofractionated RT in the post-operative setting (the prostate bed). Methods: This is an interim analysis (follow up and accrual not completed) of phase II trial of Pca patients submitted to RP and adjuvant or salvage RT. The radiation treatment was delivered using volumetric arch and image guided RT technique to a dose of 51 Gy in 15 fractions. The primary goal was to evaluate grade ≥ 2 acute urinary (GU) toxicity. Sample calculation was based on an incidence of GU toxicity of 15% with an calculated IC of 9% (6-24%). This resulted in a sample size of 61 patients. The study secondary objectives were biochemical recurrence free survival, metastasis free survival, time to hormone therapy, and overall survival. Additional objectives were gastrointestinal toxicities (GI), late GI and GU toxicities, and quality of life measurements, (using EPIC), before RT, 3, 6, 12 and 24 months after RT. Results: Sixty-one patients were enrolled in the study. Three percent presented with low risk, 13 % intermediate and 84% with high risk disease. Fifty six patients underwent salvage RT and 5 adjuvant RT. Average pre-treatment PSA was 0.27ng/mL (0.08-0.47). Median follow up is 8 months (2-23). The rate of grade ≥ 2 GU acute toxicity was 10.8% and 1 patient had urinary retention. Grade ≥ 2 acute GI toxicity rate was 13%. During follow up time, only 1 patient had biochemical failure and no distant metastasis. Post-RT PSA value diminished in 95.6% patients and average PSA value was 0.01 ng/mL (<0.003-1.18). All grades late GU, and GI toxicities rates were both 2.5%. Conclusions: In this interim analysis, hypofractionated RT to the prostate bed is reported to be a safe and effective strategy for Pca patients submitted to RP and adjuvant or salvage RT.

 

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Publikationsverlauf

Artikel online veröffentlicht:
23. Oktober 2019