Abstract P2-16-11: Impact of adjuvant trastuzumab (T) with chemotherapy on breast cancer specific and cardiac outcomes in older women with small, node-negative HER2-positive breast cancer

Abstract

Abstract Introduction: For women with high risk early breast cancer that overexpresses HER2, the role of adjuvant T with chemotherapy is well established. Although the benefits of this approach in women with small, node negative tumors are less well defined, we previously published a retrospective sequential cohort study that suggested that T with chemotherapy is active in this setting. However there are few data about the safety and efficacy of adjuvant T in older women with small, node negative HER2+ breast cancer. Thus, this we conducted a retrospective study of breast cancer specific and cardiac outcomes for this subset. Methods: From our previously reported dataset, we identified women > 60y with <2 cm, node-negative HER2+ breast cancer. We identified a “no-T” cohort of 32 women diagnosed Jan ‘02 - May ‘05 and a “T” cohort of 39 patients diagnosed May ‘05 - Dec ‘08. Electronic medical records were reviewed to examine risk factors and incidence of cardiotoxicity as well as patient outcomes including distant disease-free survival (DDFS) and overall survival (OS). Results: Women in the two cohorts had similar baseline characteristics including cardiac risk factors (Table 1). There were no cardiac events in the no-T group. In the T group, 3 patients discontinued T due to a cardiac event: 1 with asymptomatic decline in ejection fraction (EF), 1 with atrial fibrillation and dyspnea, and 1 with symptomatic EF decline associated with myocardial infarct and valvular disease. Patients in both cohorts had excellent disease control at a median follow up of 9y and 6y for the no-T and T cohorts respectively. The 3y DDFS numerically favors the T cohort, the confidence intervals are broad and overlapping (Table 1). There were no detectable differences in OS between groups. In our previous report (not selected for age), DDFS at 3yrs was 95% (90-99) and 100% in the no-T (N = 106) and T (N = 155) cohorts respectively. Conclusion: In this small retrospective study, older women with small, node negative HER2+ breast cancers had excellent disease control and a low risk of cardiotoxicity. The possible benefits of T in this setting are consistent with prior reports uncontrolled for age. Table 1 No Trastuzumab N = 32 N (%)Trastuzumab N = 39 N (%)Tumor Size (cm), median (range)1.4 (0.1-2.0)1.3 (0.5-2.0)Multifocal Disease6 (19)4 (10)Grade 324 (75)33 (85)ER Positive20 (63)20 (51)Age, median (range)66 (60-85)65 (60-82)BMI, median (range)24.7 (18.2-34.2)27.3 (18.2-47.1)Chemotherapy16 (50)39 (100)Radiotherapy23 (72)25 (64)Hypercholesterolemia11 (34)18 (46)Hypertension12 (38)13 (33)3yr DDFS (95% CI)91% (74-97)97% (83-100)3yr OS (95% CI)97% (80-100)97% (83-100) Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-11.