Early experience and quality of life prostate cancer Phase I-II SBRT trials.

Introduction: Extracranial stereotactic body radiation therapy (SBRT) allows delivering high doses per fraction with high accuracy to the prostatic gland in a low number of fractions.

Purpose/Objective(s): 1) To evaluate the feasibility and toxicity of two regimens of hypofractionated stereotactic body radiation therapy (SBRT). 2) To obtain patients self-reported quality of life (QOL) measures in two cohorts of SBRT in low- intermediate risk prostate cancer and SBRT as a boost after 60Gy of external radiation EBRT for high risk patients.

Materials/Methods: Two prospective phase I-II studies were approved by our institutional review and ethics board. Inclusion criteria were: Trial1) T1-2N0M0, Gleason Score 6–7, PSA ≤ 20 ng/mL, and IPSS 0–7. Trial 2) T3aN0M0 Gleason score 8 or less (N+risk<25%) and IPSS 0-12. Hormonal-therapy was prescribed according to risk classification. Image Guided RT with Cone Beam CT was mandatory.  Dose SBRT was delivered at a prescribed planning target volume (PTV) 35 Gy in five fractions in 5 alternative days or 9 Gy after 60 Gy 2 Gy per fraction in 30 days, using with RapidArc VMAT, with 6 MV FFF photons. CTCAE v4.0 morbidity scores were used to assess toxicities. Health-related quality of life questionnaire was administered centrally by telephone interview before treatment and during follow-up (at 3, 6 and 12 months).

Results: Forty patients have been recruited. Mean age was 70.2 years. Twenty-two patients were included in trial 1 and 18 in trial 2. According to D’Amico risk classification for trial 1), 3/22 patients were low-risk and 19/22 were intermediate risk, for trial 2) 18 patients were high risk.  All patients completed the treatment as programmed with good tolerance. No toxicity greater than grade 2 was observed. EPIC urinary values were significantly higher at 6 (96.57) and 12 months (91.59) for SBRT (5x7) vs trial 2 (81.26 and 80.49). No differences were seen in EPIC bowel scores. EPIC hormonal was higher at 6 and 12 months in the first group 85.09 and 81.57 vs 64.09 and 76.14 in the 9 Gy boost patient’s trial.

Conclusion: Both SBRT regimes with VMAT and FFF beams for low–intermediate-risk  and high risk prostate cancer are feasible and well tolerated in selected patients. Differences in EPIC hormonal QLQ measures are related to prolonged hormonal treatment in high risk patients. EPIC values related to radiation treatment are not different. Long-term follow-up is needed for assessment of late toxicity and outcomes.