A multicentre phase II study of hypofractionated stereostatic boost in intermediate risk prostate carcinoma: a 5-year analysis of the CKNO-PRO trial.

Abstract

BACKGROUND\nThe aim of this analysis was to assess the 5-year tolerance and survival in patients undergoing hypofractionated stereotactic boost after external beam radiotherapy (EBRT) for intermediate-risk prostate cancer.\n\n\nMETHODS AND MATERIAL\nBetween August 2010 and April 2013, 76 patients with intermediated-risk prostate carcinoma were included in the study. A first course delivered 46 Gy using conventional fractionation. The second course delivered a boost of 18 Gy (3x6Gy) within 10 days using stereotactic body radiation therapy (SBRT). Gastrointestinal (GI) and genitourinary (GU) toxicities were assessed according to NCI-CTCAE (v4.0). Secondary outcome measures were overall, biochemical relapse-free, relapse-free survival, PSA kinetics, and patient functional status (urinary and sexual) according to the IIEF5 and IPSS questionnaires.\n\n\nRESULTS\nSixty (79%) patients were treated by Cyberknife and 16 (21%) by linear accelerator. Median follow-up was 62 months (range, 29-69 months). The cumulative incidence of GU and GI grade ≥2 toxicities at Month 60 after the end of RT was 1.4% (95% CI: 0.1%-6.6%) and 9.3% (95% CI: 4.1%-17.1%), respectively. Biochemical relapse-free and relapse-free survival rates at 5 years were 87.4% (95% CI: 77.1%-93.2%) and 86.2% (95% CI: 75.8-92.3), respectively. The mean (SD) PSA variation within 3 months and 5 years post-RT was -1.20 ng/mL/month (0.79) and -1.30 ng/mL/year (1.05), respectively. There was no significant difference between the IPSS QoL score between inclusion and month 60. For IIEF-5 there was a significant difference between inclusion and month 60 (p=0.005) with a higher proportion of severe/non-interpretable disorders at 60 months.\n\n\nCONCLUSIONS\nThe results of the trial demonstrate that the EBRT and SBRT combination is well tolerated and yields good efficacy results. These data provide a good basis for comparing EBRT and brachytherapy boost to EBRT and SBRT boost in future prospective studies .