Introduction:
Trastuzumab and anthracyclines are mainstays of chemotherapy in breast cancer and lymphoma patients but may cause significant cardiotoxicity, which may result in alterations to chemotherapy dose, schedule, or agent. Obesity is increasingly prevalent in the United States and is a significant risk factor for both cardiovascular disease and certain cancers. We aimed to assess the relationship between obesity and the risk of developing chemotherapy-associated cardiotoxicity.

Material and methods:
A retrospective chart review was conducted of all patients who received trastuzumab or anthracyclines over a 5-year period from January 1, 2008, to December 31, 2012 at our tertiary care center in the Northeastern United States. Obesity was defined as a body mass index (BMI) ≥ 30 kg/m2. Cardiotoxicity was defined as demonstrated left ventricular ejection fraction less than 50% or demonstrated ischemia or infarction on echocardiogram or cardiac catheterization. Bivariate analyses were conducted to determine the association between demographic and clinical variables with cardiotoxicity status. Two multivariate logistic regression models were generated to assess whether BMI was independently associated with cardiotoxicity.

Results:
Of the 368 patients receiving either trastuzumab or anthracyclines, 16 patients developed cardiotoxicity. Demographically, age, race, BMI, body surface area (BSA), and overall weight did not differ between the patients who developed cardiotoxicity and those who did not. The mean dose of anthracycline and trastuzumab did not differ between the patients who developed cardiotoxicity and those who did not. Obesity was not found to increase the odds of developing cardiotoxicity and was slightly protective. A non-significant decrease in the odds of developing cardiotoxicity was found for every one-unit increase in BMI. In a multivariable model using BMI as a continuous predictor and controlling for BMI, age, hypertension, chemotherapy type, and coronary artery disease, the only significant predictor of cardiotoxicity was a previous history of arrhythmia.

Conclusions:
Obesity was not a significant risk factor for patients developing cardiotoxicity from trastuzumab- or anthracycline-based chemotherapy and may be a protective factor for cardiotoxicity. Additional studies with greater statistical power are needed to further evaluate this effect and independently evaluate obesity as a risk factor for cardiotoxicity.