Citation: International Journal of Radiation Oncology Biology Physics. 2019, 105(1)
Author: Brand D.H.; Tree A.; Morrison K.; Naismith O.; van As N.; Ostler P.; van der Voet H.; Loblaw D.A.; Chu W.; Ford D.;Tolan S.; Jain S.; Martin A.; Staffurth J.; Brown S.; Burnett S.; Griffin C.; Hinder V.; Hall E.; Duffton A.
Abstract: Purpose/Objective(s): External beam radiotherapy (EBRT) is one of several curative treatment options for localised prostate cancer (LPCa). Moderate hypofractionation of EBRT (2.5-3Gy per fraction (f)) has been shown non-inferior to conventional 2 Gy/f by multiple large randomised controlled trials (RCTs). Low and comparable rates of clinician reported acute toxicity have been reported in the Stereotactic Body Radiotherapy (SBRT) and CFMHRT treated groups in PACE-B. This study reports patient reported outcomes (PRO) for
bladder and bowel, related to acute toxicity. Materials/Methods: PACE (NCT01584258) is a phase III, openlabel, multiple-cohort RCT. Patients eligible for the PACE-B cohort had LPCa, stage T1-T2, <= Gleason 3 + 4, PSA <= 20 ng/mL and were either unsuitable for surgery or chose EBRT. Randomisation was 1:1 between SBRT (36.25Gy/5f over 1-2 weeks (wks)) or CFMHRT (78Gy/39f over 7.5 wks or 62Gy/20f over 4 wks, determined by centre's standard schedule). Androgen deprivation therapy was not allowed. PRO metrics included: Expanded Prostate Cancer Index Composite 26 (EPIC-26) at baseline, 2, 4, 12 wks post radiotherapy (RT); International Prostate Symptom Score (IPSS) at baseline, 2, 4, 8, 12 wks post-RT. The proportion of patients with EPIC-26 change scores (baseline to 12 wks) greater than minimum clinically important differences (MCID) in each subdomain (urinary incontinence (UI) 8 points, urinary obstructive (UO) 6 points, bowel 5 points) are reported. IPSS total scores were categorised as none, mild, moderate, severe and compared between SBRT and CFMHRT at 12 weeks. Comparisons between SBRT and CFMHRT were based on chi-squared tests with p < 0.01 considered statistically significant.
Result(s): Between 07/12/2012 and 04/01/18, 38 centres randomised 874 pts: 431 received CFMHRT; 414 SBRT. Patient and disease characteristics were similar between CFMHRT and SBRT: mean age: 69.5 vs 69.3 years; Intermediate risk: 91.4% vs 92.5%; T-stage >=T2b: 51.7% vs 56.6%; Gleason Score 3+4: 80.7% vs 85.5%; PSA 10-20 ng/mL: 30.9% vs 31.6%. EPIC MCID deteriorations, for CFMHRT vs SBRT, occurring by subdomain were: UI 67/326 (20.6%) vs 51/323 (15.8%), p=0.12; UO 108/313 (34.5%) vs 105/306 (34.3%), p=0.96; bowel
91/322 (28.2%) vs 90/323 (27.9%), p=0.91. Proportion of patients with baseline none/mild/moderate/severe IPSS symptoms were CFMHRT: 5.4%/51.1%/37.3%/6.2% and SBRT: 4.5%/54.5%/35.6%/5.4%. At 12 weeks no differences were seen in IPSS scores between CFMHRT and SBRT: 2.8%/57.9%/36.8%/2.5% vs 3.4%/54.8%/36.7%/5.1% (p=0.34, test for trend).
Conclusion(s): These data corroborate the prior clinician-reported acute toxicity findings for bladder and bowel outcomes, with no significant differences in key PRO measures.
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