Fred Hutchinson Cancer Center
Dr. Heather Greenlee
For example, certain chemotherapy drugs may confer higher risk in breast cancer survivors of normal weight, whereas they may lower stroke risk in those who are obese, according to Heather Greenlee, ND, PhD, a public health researcher and naturopathic physician with the Fred Hutchinson Cancer Research Center in Seattle.
In postmenopausal women with breast cancer, aromatase inhibitors may increase cardiovascular risk, while tamoxifen appears to reduce the risk of incident dyslipidemia, she said.
The findings are from separate analyses of data from studies presented during a poster discussion session at the symposium.
Breast cancer treatment and cardiovascular effects: The role of weight
In one analysis, Dr. Greenlee and colleagues examined outcomes in 13,582 breast cancer survivors with a median age of 60 years and median follow-up of 7 years to assess whether cardiovascular disease (CVD) risk associated with specific breast cancer therapies varies by body mass index (BMI) category at diagnosis.
Many routinely used breast cancer therapies are cardiotoxic, and being overweight or obese are known risk factors for CVD, but few studies have assessed whether BMI modifies the effect of these treatment on cardiovascular risk, Dr. Greenlee explained.
After adjusting for baseline demographic and health-related factors, and other breast cancer treatment, they found that:
- Ischemic heart disease risk was higher among normal-weight women who received anthracyclines, compared with those who did not (hazard ratio, 4.2). No other risk associations were observed for other breast cancer therapies and BMI groups.
- Heart failure/cardiomyopathy risk was higher among women with normal weight who received anthracyclines, cyclophosphamides, or left-sided radiation, compared with those who did not (HRs, 5.24, 3.27, and 2.05, respectively), and among overweight women who received anthracyclines, compared with those who did not (HR, 2.18). No risk associations were observed for women who received trastuzumab, taxanes, endocrine therapy, or radiation on any side, and no risk associations were observed for women who were obese.
- Stroke risk was higher in normal-weight women who received taxanes, cyclophosphamides, or left-sided radiation versus those who did not (HRs, 2.14, 2.35, and 1.31, respectively), and stroke risk was lower in obese women who received anthracyclines, taxanes, or cyclophosphamide, compared with those who did not (HRs, 0.32, 0.41, and 0.29, respectively). No risk associations were observed for trastuzumab, endocrine therapy, or radiation on any side, and no risk associations were observed for women who were overweight.
The lack of associations noted between treatments and heart failure risk among obese patients could be caused by the “obesity paradox” observed in prior obese populations, the investigators noted, adding that additional analyses are planned to “examine whether different dosage and duration of breast cancer therapy exposures across the BMI groups contributed to these risk associations.”