Influence of Ile655Val polymorphism on trastuzumab-induced cardiotoxicity in early-stage HER2 positive breast cancer
Ljubica Vazdar, Ivo Darko Gabrić, Ivan Kruljac, Hrvoje Pintarić, Robert Šeparović, Lora Stanka Kirigin Biloš, Mirjana Pavlović, Ana Tečić Vuger, Mario Štefanović
Abstract
Trastuzumab has improved the prognosis of HER2 positive breast cancer, but cardiotoxicity remains a concern. We aimed to identify risk factors for trastuzumab-induced cardiotoxicity, with an emphasis on the HER2 Ile655Val single nucleotide polymorphism. This single-center case-control study included 1056 patients with early-stage HER2 positive breast cancer that received adjuvant trastuzumab. Cardiotoxicity was defined as a decline in left ventricular ejection fraction (LVEF) > 15% in patients without previous cardiomyopathy, or > 10% in patients with baseline LVEF of < 50%. Patient characteristics and cardiac parameters were compared in 78 (7.38%) cases and 99 randomly assigned controls, and the polymorphism was genotyped using real-time polymerase chain reaction. Cardiotoxicity was independently associated with advanced age (P = 0.024), lower body mass index (P = 0.023), left breast involvement (P = 0.001), N3 status (P = 0.004), diabetes (P = 0.016), and a family history of coronary artery disease (P = 0.019). Genotype distribution was as follows: A/A (Ile/Ile) was found in 111 (62.7%) patients, A/G (Ile/Val) in 60 (33.9%) patients, and G/G (Val/Val) in 6 (3.4%) patients. The genotype was not associated with cardiotoxicity or the severity of heart failure, reversibility, and recovery time. We found no association between the HER2 Ile655Val polymorphism and trastuzumab-induced cardiotoxicity; therefore, we do not recommend routine cardiotoxicity-risk stratification using this polymorphism.