No increase in incidence or risk of recurrence of breast cancer in 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.

STUDY DESIGN: Retrospective matched cohort study.

MAIN 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 treatment 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 recurrence in patients with a history of BC in 1:1, 1:2 and 1:3 matches.

RESULTS: 1728 ospemifene users and 3456 untreated patients met the inclusion and matching criteria for assessing 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.

CONCLUSION: No differences were observed in the BC incidence and recurrence rates in ospemifene users compared with matched controls.