(ChemotherapyAdvisor) – Treatment of breast cancer patients with regimens containing trastuzumab increases their risk of cardiotoxicity, according to researchers of the University of Milan, Italy. The study, entitled “Trastuzumab-Containing Regimens for Early Breast Cancer,” was published in the online edition of The Cochrane Library on April 18. 

The primary aim of this study is assessment of efficacy and safety data for trastuzumab, when used alone or in combination with standard chemotherapy, for the treatment of HER2-positive early stage breast cancer. For the assessment, the authors searched the Cochrane Breast Cancer Group’s (CBCGs) Specialized Trials Register to search, in several databases, for randomized controlled trials (RCTs) occurring prior to February 2010.

Data were collected from published and unpublished RCTs and used to calculate hazard ratios (HRs) for time-to-event outcomes and risk ratio (RRs) for outcomes; further analyses within subgroups included duration (less or greater than six months) and concurrent or sequential trastuzumab administration. Eight studies, involving 11,991 patients, were selected for analysis.

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The authors reported that the “combined HRs for overall survival (OS) and disease-free survival (DFS) significantly favored the trastuzumab-containing regimens (HR=0.66; 95% confidence interval (CI) 0.57 to 0.77, P<0.00001; and HR=0.60; 95% CI 0.50 to 0.71, P<0.00001, respectively). Trastuzumab significantly increased the risk of congestive heart failure (RR=5.11; 90% CI 3.00 to 8.72, P<0.00001); and left ventricular ejection fraction decline (RR=1.83; 90% CI 1.36 to 2.47, P=0.0008).”

The authors concluded: “Trastuzumab significantly improves OS and DFS in HER2-positive women with early and locally advanced breast cancer, although it also significantly increases the risk of CHF and LVEF decline. Shorter duration of therapy may reduce cardiotoxicity and maintain efficacy…”