Genitourinary Cancer

SS 28 - GU 3 - New Insights Into Treatment Intensification Strategies for Prostate Cancer

205 - Toxicity and Biochemical Outcomes After Dose Intensified Post-Operative Radiation Therapy for Prostate Cancer: A Randomized, Controlled, Phase 3 Trial

Tuesday, October 23
3:55 PM - 4:05 PM
Location: Room 007 A/B

Toxicity and Biochemical Outcomes After Dose Intensified Post-Operative Radiation Therapy for Prostate Cancer: A Randomized, Controlled, Phase 3 Trial
X. Qi1, H. Z. Li1, X. S. Gao1, R. Wang1, S. B. Qin1, and X. Y. Li2; 1Department of Radiation Oncology, Peking University First Hospital, Beijing, China, 2Department of Medical Statistics, Peking University First Hospital, Beijing, China

Purpose/Objective(s): There was very little high-level evidence about which radiation therapy (RT) regimen was more effective for prostate cancer after radical prostatectomy (RP). In 2011, we began the randomized, controlled, phase 3 trial to investigate the effect of dose intensified post-operative RT. Patients were randomly assigned to either 66Gy/33f or 72Gy/36f. The aim of current analysis was to compare toxicity, urinary continence recovery and biochemical outcomes.

Materials/Methods: This trial recruited patients who had received RP for a histologically confirmed adenocarcinoma of the prostate, and who had stage pT3-4, positive surgical margins, pN+ or who had rising PSA of 0.2ng/ml following RP. Eligible patients were randomly assigned (1:1) to receive either 66Gy or 72Gy. IG-VMAT techniques was used. The primary endpoint was biochemical progression-free survival (PSA increase of 0.2 ng/ml or greater from the post-RT nadir, a continued rise in PSA despite RT or the initiation of salvage ADT). The second endpoints were acute and late toxicity, and urinary continence recovery. Genitourinary (GU) and gastrointestinal (GI) toxicity was assessed using RTOG-EORTC criteria. Incontinence was assessed by International Consultation on Incontinence Modular Questionnaire Short Form (ICIQ-SF) at start/end of RT and 1 year afterward.

Results: Between Sep. 2011 and Nov. 2016, 144 patients were randomly assigned, 71 to 66Gy group and 73 to 72Gy group. The median follow-up time was 42 months (range: 10-71 mos). 3-year biochemical progression-free survival was 73.8% vs. 76.6% in 66Gy vs. 72Gy group. For acute toxicity no significant differences were seen between the two groups. Acute GU toxicity grade 1 and 2 were reported as 74.6% and 83.6%, 5.6% and 4.4% respectively. Late GU toxicity grade 1 and 2 were 18.3% and 8.2%, 8.5% and 11.0%. Grade 3 GU toxicity was observed in one patient in 72Gy group. For acute GI toxicity, these figures were 78.9% and 84.9%, 11.3% and 8.2%. Late GI grade 1 and 2 were 9.9% and 8.2%, 1.4% and 2.7%. No significant differences between both groups were seen for late GI and GU toxicity. At baseline 48 (33.3%) of patients were incontinent (16.7% mild, 13.9% moderate, 2.8% severe). Of these 48 patients, continence was recovery one year after RT by 33.3% vs. 28.6% with 66Gy vs. 72Gy. 63.0% vs. 66.7% of patients remained stable. Only 2 patients felt more seriously after RT.

Conclusion: Our study suggested that dose-intensified RT was associated with low rates of acute and late grade 2-3 GU/GI toxicity, and had no obviously impact on one-year urinary continence recovery. However, the long-term survival outcomes needed to be further explored.

Author Disclosure: X. Qi: None. X. Gao: None. R. Wang: None.

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