Breast cancer patients and survivors may have a heightened risk of cardiovascular disease (CVD) and require careful monitoring, particularly when treatment includes drugs that can damage the heart, according to a scientific statement from the American Heart Association (AHA).
Breast cancer patients, particularly older patients, are more likely to die of CVD than breast cancer, and patients may benefit from management strategies that weigh the cancer benefits versus heart risks, authors of the statement wrote in Circulation.
“Any patient who is going to undergo breast cancer treatment, whether they have heart disease at the beginning or not, should be aware of the potential effects of the treatment on their heart,” writing group chair Laxmi Mehta, MD, said in a statement. “This should not deter or scare patients from undergoing breast cancer treatment but should allow them to make informed decisions with their doctor on the best cancer treatment for them.”
The association between breast cancer and CVD begins with overlapping risk factors, including older age, obesity, and smoking. As much as 80% of attributable risk for CVD can be eliminated by attention to modifiable risk factors, including a healthy diet, abstinence from tobacco, maintenance of a healthy weight, blood pressure control, a favorable lipid profile, diabetes management, and physical activity. Some evidence suggests that following the AHA Life’s Simple 7 lifestyle-based health campaign may help lower the risk of cancer.
The evidence regarding postmenopausal hormone replacement therapy (HRT) is mixed. Data from the Nurses Health Study showed an increased risk of breast cancer in women taking HRT. In contrast, data from the Women’s Health Initiative suggested the effect varied according to the type of hormones used and whether a woman had an intact uterus. Several studies have found positive associations between HRT and CVD in older postmenopausal women and women with existing coronary disease.
Authors of the AHA statement concluded, “These data confirm that postmenopausal HRT is associated with both breast cancer and CVD … and this is a potentially modifiable risk factor for both diseases.”
With regard to potential adverse effects of cancer treatment on the heart, the AHA panel noted that two widely used cancer medications — doxorubicin and trastuzumab (Herceptin) — can damage heart tissue and reduce the heart’s functional capacity, effects associated with the development of heart failure.
The anthracycline class of chemotherapeutic drugs can trigger abnormal heart rhythms, which may be benign or potentially life-threatening. Antimetabolites can cause vasospasm that produces symptoms ranging from chest pain to heart attack.
Among options for hormonal breast cancer therapy, tamoxifen favorably affects lipid profiles, but studies showed no beneficial effect on CVD risk. Tamoxifen adversely affects clotting parameters and increases the risk of venous thrombosis and thromboembolism. Aromatase inhibitors (AI) are associated with a lower risk of clot-related disorders as compared with tamoxifen. Pooled data and meta-analyses suggested that AI use modestly but significantly increases the risk of CVD versus tamoxifen.
“Despite the small absolute risk, the clinical relevance of these findings could be high in specific populations at risk,” the AHA panel concluded.
Radiation therapy can affect blood vessels in ways that make patients more likely to develop coronary artery disease. Despite improvements in technology and delivery techniques, “irradiation to smaller volumes of the heart results in cardiac perfusion defects,” the AHA panel stated.
Certain clinical management strategies may help reduce or prevent the adverse effects of breast cancer therapy. For example, some studies suggested that administration of doxorubicin by slow infusion rather than bolus may minimize damage to the heart. Additionally, the drug dexrazoxane is approved for minimizing heart damage in patients with metastatic breast cancer treated with high doses of doxorubicin.
Heart health should figure into the initial planning of breast cancer treatment, including drug choices and follow-up monitoring during treatment, said Mehta. In some cases, pre-existing heart conditions may guide the course of cancer care, or cancer therapy may adversely affect the heart and necessitate changes in treatment plans.
“Ideal breast cancer outcomes are reliant on coexisting cardiovascular health along the entire journey of breast cancer treatment,” the AHA panel concluded.
Mehta disclosed no relevant relationships with industry. One or more coauthors disclosed relationships with Boehringer INgelheim, Amarin, Amgen, Genentech, AstraZeneca, Lilly, NovoNordisk, Pharmacosmos, Sunovion, and Hoffman La Roche