Abstract GS6-02: A randomized, double-blind, placebo-controlled trial of oxybutynin (Oxy) for hot flashes (HF): ACCRU study SC-1603

• Published in: Cancer research (Chicago, Ill.) Ill.), 2019-02, Vol.79 (4_Supplement), p.GS6-02-GS6-02
• Main Authors: Leon-Ferre, RA, Novotny, PJ, Faubion, SS, Ruddy, KJ, Flora, D, Dakhil, C, Rowland, KM, Graham, ML, Le-Lindqwister, N, Loprinzi, CL
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.SABCS18-GS6-02

Background: HF occur in about 75% of midlife women and are associated with quality of life disruption and premature endocrine therapy discontinuation among breast cancer survivors. Estrogen therapy, effective for HF, is contraindicated in hormone receptor-positive breast cancer (BC). Previous studies have suggested that Oxy could be effective in managing HF. Methods: This randomized, placebo (P)-controlled trial enrolled women who had experienced HF ≥28 times per week over >30 days and of sufficient severity to seek treatment. Patients (pts) were randomized to receive oral Oxy at two doses: 2.5mg BID for 6 weeks (Oxy2.5), 2.5mg BID for a week with subsequent increase to 5mg BID (Oxy5), or matching P, in equal ratios. Baseline and monthly questionnaires were administered including a HF diary, the HF related daily interference scale (HFRDIS) and a symptom experience questionnaire. The primary endpoint was intra-patient change in weekly HF score and frequency from baseline to end of study compared using Kruskal-Wallis tests. Results: 150 pts were accrued between 2/23/2017-3/5/2018. 4 pts cancelled before starting treatment and were excluded from analyses. This interim report includes the first 104 pts for which at least one post-baseline evaluation was available. Baseline characteristics were well-balanced between the arms. Sixty-two percent were on tamoxifen or an aromatase inhibitor for the duration of the study. Pts on both Oxy doses had a significantly greater reduction in HF score and frequency compared to P. Pts on Oxy2.5 had a mean change in HF score of -10 (SD 7.4) vs -5.1 (SD 9.7) with P, p=0.003; and a mean change in average weekly number of HF of -4.6 (SD 3.1) vs -2.3 (SD 3.9), p=0.002. Pts on Oxy5 had a mean change in HF score of -16.2 (SD 5.1) vs -5.1 (SD 9.7) with P, p