RESUMO
PURPOSE: We aimed to determine if ultrahypofractionated proton therapy delivered via stereotactic body proton therapy (SBPT) is noninferior to conventionally fractionated proton therapy (CFPT) in patients with early prostate cancer. METHODS AND MATERIALS: This study was a multicenter, randomized, controlled, noninferiority phase 3 trial that included patients with histologically confirmed low-risk prostate adenocarcinoma defined by Gleason score grouping 1, Prostate-specific antigen <10 ng/mL, and clinical stage T1-T2a N0 M0 according to 7th edition of the American Joint Committee on Cancer tumor-node-metastasis cancer staging system. Eligible participants were randomly assigned initially at a 1:1 ratio and later at a 2:1 ratio to SBPT (38 Gy in 5 fractions) or CFPT (79.2 Gy in 44 fractions). The primary endpoint was freedom from failure (FFF) at 2 years from the date of randomization. Noninferiority for FFF was determined based on 1-sided confidence intervals. Toxicities were compared at different time points using Fisher's exact test. Health-related quality-of-life (HRQoL) was analyzed at different time points using a mixed-effects linear model. This trial is registered with ClinicalTrials.gov, NCT01230866, and is closed to accrual. RESULTS: Between December 10, 2010, and September 29, 2020, 144 patients were enrolled and 135 were randomly assigned (90 to the SBPT group and 45 to the CFPT group). The median follow-up was 5 years (IQR, 3.9-5.2). The 2-year FFF was 100% for both groups, with the 1-sided 5-year risk difference in FFF between groups reported as 2.63% (90% CI, -1.70% to 6.96%), favoring the SBRT arm, thus fulfilling the prespecified criteria for noninferiority of SBPT compared with CFPT. Rates of gastrointestinal and genitourinary G2 and G3 toxicities did not differ significantly between groups. Further, HRQoL metrics did not differ significantly between groups over the study's median follow-up. CONCLUSIONS: SBPT is noninferior to CFPT regarding FFF, with similar long-term genitourinary and gastrointestinal toxicity rates and minimal impact in patient-reported HRQoL over time.
RESUMO
Purpose: Our objective was to report the quality of life (QoL) analysis and toxicity in patients with intermediate-risk prostate cancer treated with or without androgen deprivation therapy (ADT) in Proton Collaborative Group (PCG) GU003. Methods and Materials: Between 2012 and 2019, patients with intermediate-risk prostate cancer were enrolled. Patients were randomized to receive moderately hypofractionated proton beam therapy (PBT) to 70 Gy relative biologic effectiveness in 28 fractions to the prostate with or without 6 months of ADT. Expanded Prostate Cancer Index Composite, Short-Form 12, and the American Urological Association Symptom Index instruments were given at baseline and 3, 6, 12, 18, and 24 months after PBT. Toxicities were assessed according to Common Terminology Criteria for Adverse Events (version 4). Results: One hundred ten patients were randomized to PBT either with 6 months of ADT (n = 55) or without ADT (n = 55). The median follow-up was 32.4 months (range, 5.5-84.6). On average, 101 out of 110 (92%) patients filled out baseline QoL and patient-reported outcome surveys. The compliance was 84%, 82%, 64%, and 42% at 3, 6, 12, and 24 months, respectively. Baseline median American Urological Association Symptom Index was comparable between arms (6 [11%] ADT vs 5 [9%] no ADT, P = .359). Acute and late grade 2+ genitourinary and gastrointestinal toxicity were similar between arms. The ADT arm experienced a QoL decline of mean scores in the sexual (-16.1, P < .001) and hormonal (-6.3, P < .001) domains, with the largest time-specific hormonal differences at 3 (-13.8, P < .001) and 6 (-11.2, P < .001) months. The hormonal QoL domain returned to baseline 6 months after therapy. There was a trend to baseline in sexual function 6 months after completion of ADT. Conclusions: After 6 months of ADT, sexual and hormonal domains returned to baseline 6 months after completion of treatment for men with intermediate-risk prostate cancer.