Effect of Doxorubicin Plus Cyclophosphamide on Left Ventricular Ejection Fraction in Patients With Breast Cancer in the North Central Cancer Treatment Group N9831 Intergroup Adjuvant Trial

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Abstract
Purpose: To evaluate changes in left ventricular ejection fraction (LVEF) after four cycles of adjuvant doxorubicin plus cyclophosphamide (AC) in women with human epidermal growth factor receptor 2–positive (node-positive or node-negative) breast cancer enrolled onto the North Central Cancer Treatment Group N9831 Intergroup Adjuvant Trial. Patients and Methods: Patients were randomly assigned to receive standard doxorubicin (60 mg/m2) plus cyclophosphamide (600 mg/m2) every 3 weeks for four cycles followed by (1) weekly paclitaxel for 12 weeks; (2) weekly paclitaxel for 12 weeks, then weekly trastuzumab for 52 weeks; or (3) weekly paclitaxel plus trastuzumab for 12 weeks, then weekly trastuzumab for 40 weeks. LVEF was monitored before and after AC. Results: Of the 1,576 eligible patients who completed AC, 1,458 had pre- and post-AC LVEF measurements taken using the same methodology (multiple-gated acquisition in 1,153 patients and echocardiogram in 305 patients). Among these 1,458 patients, 745 (51.1%) had ≤ 15% decrease in LVEF and LVEF that remained at or above the radiologic lower limit of normal (LLN); 42 patients (2.9%) had ≤ 15% decrease in LVEF and LVEF that decreased to or below the LLN; and 37 patients (2.5%) had an LVEF decrease of more than 15%. There was grade 2 LVEF toxicity in 96 (6.6%) of the 1,458 patients. Conclusion: Standard AC chemotherapy is associated with frequent decreases in LVEF, which are noted when measured 3 weeks after completion of the fourth cycle. Patients are being observed to determine the long-term significance of this and the potential impact on subsequent treatment options.