Outcomes Related To Delayed Initiation Of Anti-Her 2 Therapy In Pregnant Her2 Positive Breast Cancer Patients.

e12059Background: Overexpression of HER2 is associated with aggressive breast cancers. In non-pregnant HER2+ breast cancer patients, anti-HER2 therapy is usually initiated after surgery or in the neoadjuvant setting. However, for pregnant HER2+ breast cancer patients, anti-HER2 therapy must be delayed until after delivery due to fetal toxicity. We describe here the outcomes of pregnant patients with HER2+ breast cancer at a single center. Methods: Twenty-three pregnant HER2+ breast cancer patients were treated between November 1989 to October 2016. Median age at diagnosis was 31.8. (Table 1) We report Kaplan-Meier estimates of OS from diagnosis and PFS from surgery. The effect of time from diagnosis to anti-HER2 therapy (TTH) on OS and PFS from HER2 therapy initiation was assessed using Cox proportional hazards regression models. Results: Seventeen patients received anti-HER2 therapy after delivery, 6 did not – 4 were treated prior to the use of HER2 therapies, and 2 were lost to follow-up. Median TTH was...