PV QA 1 - Poster Viewing Q&A 1
Purpose/Objective(s): There is a strong radiobiologic rationale for utilizing hypo-fractionated radiation to treat prostate cancer (CaP). The application of stereotactic techniques may potentially further extend these clinical benefits to patients and society by decreasing cost, improving access and decreasing patient/caregiver burden by delivering equivalent outcomes in five fractions. The trial is an international randomized trial evaluating accelerated hypofractionation RT 36.25 gy in 5 fractions (AHRT) to 70.2gy in 26 fractions extended hypofractionation (EHRT). The planned accrual is 458 patients with a primary endpoint of freedom from biochemical failure or biopsy positivity disease two years after treatment with a 12% noninferiority margin. Should the five fractions be non inferior for outcome, acute and late toxicity, to protracted therapy; this would be the preferred option for low and intermediate risk CaP. However, concerns about toxicity persist. Herein we present the early toxicity and PRO for the first 54 patients.
Materials/Methods: Men were randomized between 36.25 gy in 5 fx to 70.2gy in 26 fx and were stratified by risk group, prostate size and ADT. Eligible patients included low/intermediate risk prostate cancer cT1-2, N0 M0, Gl 6-7, PSA <20 with an IPSS≤ 12. Intermediate risk patients received up to six mo. of ADT. IPSS scores were obtained prior to treatment, last week of treatment at 6 wks., 3 mo. and then every 6 mo.; EPIC-SF12/Max-PC prior to treatment 6 wks., 3 mo. and then every 6 mo. Toxicity (CTCAE4.0) at baseline, weekly during treatment, 6 wks., 3 mo. and then every 6 mo. Cumulative incidence estimation was used to calculate toxicity incidence rate and Mann-Whitney test was used to compare QoL scores between two arms. All p-values were two-sided.
Results: As of Jan. 2017, 54 pts had completed treatment, with 11.5 mo. median follow-up (mean 17.2). 70% of the patients were intermediate risk. Patients were evenly distributed by age, Gleason score, t stage, risk group, race and ADT use. Between the two arms there was no difference in the cumulative incident of grade 2+ GU toxicity (P=0.97) or GI toxicity (P=0.181). 15 mo. rates were 19%v 12% GU, and 12% v 0% GI. One grade 3 toxicity (EHRT) was observed. There was no significant difference in EPIC-SF12 or Max-PC scores at any time point between the 2 arms in sum score or change from baseline. For IPSS there were statistically significant differences at 6wks (p=0.0049), 9mo (p=0.0009), 15mo (p=0.0076) in favor of AHRT (lower IPSS score).
Conclusion: There were no differences in early GI and GU toxicities or PRO measures between AHRT and EHRT. This early analysis suggests that AHRT has decreased urinary symptoms as measured by IPSS. While we await clinical efficacy data, these data suggest little difference in toxicity with AHRT, partially alleviating concerns related to the toxicity of this regimen.
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