Longer-term cardiac safety and outcomes of dose dense (dd) doxorubicin and cyclophosphamide (AC) followed by paclitaxel (T) and trastuzumab (H) with and without lapatinib (L) in patients (pts) with early breast cancer (BC).

579 Background: The addition of H to chemotherapy has improved outcomes in HER2-positive early BC. This approach is associated with (w/) an increased risk (<4%) of congestive heart failure (CHF). Dose-dense (every 2 weeks) anthracycline-taxane therapy (Rx) improves survival compared to the every 3 week schedule and can be combined w/ anti-HER2 Rx w/ no increased risk of cardiotoxicity. We report the long-term incidence of NYHA Class III/IV CHF in 2 phase II studies. Methods: We conducted a retrospective review of pts w/ HER2 + BC treated at MSKCC on two trials: In trial A - pts received dd AC (60/600 mg/m2) × 4 → T (175mg/m2) × 4 (w/ pegfilgrastim) w/ H × 1 year. Trial B differed w/ use of weekly T (80mg/m2) × 12 and addition of L (1000mg orally daily) × 1 year. Left ventricular ejection fraction (LVEF) was assessed by a multi-gated acquisition scan serially throughout Rx. Results: Trial A enrolled 70 pts w/ a median age of 49 yrs (range, 27-72) and median baseline LVEF of 68% (range 55-81%); 41/68 (69%) ...