No increase in incidence or risk of recurrence of breast cancer in T ospemifene-treated patients with vulvovaginal atrophy (VVA)

Objective: To estimate the incidence and recurrence of breast cancer (BC) in patients with vulvovaginal atrophy (VVA) treated with ospemifene and matched untreated VVA patients using real-world data.\r\nStudy design: Retrospective matched cohort study.\r\nMain Outcome Measures: VVA patients were identified from the 2011–2018 US MarketScan® insurance claims database. For incidence, ospemifene-treated VVA patients without evidence of BC prior to index treat- ment were matched to two untreated VVA controls similarly without history of BC on age, index VVA year, geographic region, Charlson Comorbidity categories, and follow-up time. BC after the index treatment was identified by BC diagnosis codes, mastectomy, chemotherapy, or radiation procedure. Incidence rate, rate ratio (RR) and their 95 % confidence intervals (CI) were calculated. The process was repeated to estimate BC re- currence in patients with a history of BC in 1:1, 1:2 and 1:3 matches.\r\nResults: 1728 ospemifene users and 3456 untreated patients met the inclusion and matching criteria for asses- sing incidence. The average number of days for which ospemifene was supplied was 314 (standard deviation [SD] = 340). Average follow-up time from index treatment was 937 days (SD = 392) for treated patients and 915 days (SD = 396) for controls. BC incidence rates per 1000 person-years was 2.03 (95 % CI: 1.06−3.91) for treated patients and 3.53 (95 % CI: 2.49−4.99) for controls (RR = 0.58, 95 % CI: 0.28−1.21). No difference in recurrence was observed between ospemifene-treated and matched untreated patients. Ten (32.3 %) treated vs. 25 (40.3 %) controls in the 1:2 matched analysis had a recurrence.\r\nConclusion: No differences were observed in the BC incidence and recurrence rates in ospemifene users com- pared with matched controls.