Hypofractionated stereotactic boost in intermediate risk prostate carcinoma: Preliminary results of a multicenter phase II trial (CKNO-PRO)

PURPOSE: Dose escalation may improve curability in intermediate-risk prostate carcinoma. A multicenter national program was developed to assess toxicity and tumor response with hypofractionated stereotactic boost after conventional radiotherapy in intermediate-risk prostate cancer. METHODS AND MATERIAL: Between August 2010 and April 2013, 76 patients with intermediated-risk prostate carcinoma were included in the study. A first course delivered 46 Gy by IMRT (68.4% of patients) or 3D conformal radiotherapy (31.6% of patients). The second course delivered a boost of 18 Gy (3x6Gy) within 10 days. Gastrointestinal (GI) and genitourinary (GU) toxicities were evaluated as defined by NCI-CTCAE (v4.0). Secondary outcome measures were local control, overall and metastasis-free survival, PSA kinetics, and patient functional status (urinary and sexual) according to the IIEF5 and IPSS questionnaires. RESULTS: The overall treatment time was 45 days (median, range 40–55). Median follow-up was 26.4 months (range, 13.6–29.9 months). Seventy-seven per cent (n = 58) of patients presented a Gleason score of 7. At 24 months, biological-free survival was 98.7% (95% CI, 92.8–99.9%) and median PSA 0.46 ng/mL (range, 0.06–6.20 ng/mL). Grade ≥2 acute GI and GU toxicities were 13.2% and 23.7%, respectively. Grade ≥2 late GI and GU toxicities were observed in 6.6% and 2.6% of patients, respectively. No grade 4 toxicity was observed. CONCLUSIONS: Hypofractionated stereotactic boost is effective and safely delivered for intermediate-risk prostate carcinoma after conventional radiation. Mild-term relapse-free survival and tolerance results are promising, and further follow-up is warranted to confirm the results at long term. TRIAL REGISTRATION: ClinicalTrials.gov NCT01596816.