P1-08-15: Pattern of Cardiac Monitoring and Risk of Trastuzumab Associated-Cardiac Dysfunction in a Clinical Practice: A Population Based Study.

Abstract

Abstract Background: Adjuvant trastuzumab therapy (ATT) in women with early-stage HER2+ breast cancer has been associated with significant reduction in the disease recurrence and mortality. Cardiac dysfunction (CD) is a known serious adverse effect of ATT. Although periodic cardiac monitoring is recommended during ATT, little is known about pattern of cardiac monitoring and incidence of CD in a clinical setting. The study aimed to determine extent of cardiac monitoring and rate of CD during ATT and to identify factors correlated with CD. Methods: Medical records of women with localized HER+ breast cancer diagnosed between the years 2005–2007 in the province of Saskatchewan was reviewed. Women with advanced or recurrent disease or if they were treated in the setting of an adjuvant trastuzumab trial were excluded. A logistic regression analysis was performed to determine various clinical variables correlated with CD. Results: A total 116 eligible women with median age of 54 yrs (range: 27–74) and median BMI of 27 (range: 44–17) were indentified. 40% had a cardiac risk factor & 30% were premenopausal. 51% had node positive & 53% had ER or PR+ breast cancer. 92% received anthracycline-based chemotherapy and 23% received sequential ATT. Of 62 patients with ER/PR+ breast cancer, 61% received adjuvant aromatase inhibitors. Baseline cardiac assessment was performed in 93% women. 98% women underwent periodic cardiac monitoring during ATT, 55% had monitoring performed at the interval of 3–4 months & 82% women had monitoring performed at the interval of 3–6 months. Mean baseline cardiac ejection fraction (EF%) prior to the commencement of chemotherapy and ATT were 65% & 63.9% respectively (p=NS). CD was observed in 32 (28%) women and only 4% were symptomatic. Trastuzumab was interrupted in 34%, and was discontinued in 20% women. Of 32 women with CD, 59% were referred to a cardiologist and 53% were treated with medication. CD was reversible in 84% cases. On multivariate analysis adjuvant aromatase inhibitor therapy was significantly correlated with cardiac dysfunction (Odd ratio 6.9 [95% CI: 1.4−33.0]). During the follow up period 18% women developed recurrent disease and 16% were died. Conclusions: Our results confirm high compliance with cardiac monitoring, though not as frequently as recommended in the clinical trial setting. Overall the rate of symptomatic decline in cardiac function was similar to the rate reported in the clinical trials, however, a relatively higher incidence of asymptomatic decline in the left ventricle EF% was noted. Among various variables examined, adjuvant aromatase inhibitor therapy was associated with an increased risk of CD. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-08-15.