Some cancer survivors could have increased risk for heart problems after hormone therapy

Hormone therapies used to treat breast and prostate cancers can raise the risk for a heart attack and stroke, according to a new scientific report that advises close monitoring.

The risk is even higher for people who have two or more risk factors for cardiovascular disease, such as high blood pressure, high cholesterol, obesity, smoking or a family history of heart disease or stroke, according to the scientific statement issued Monday by the American Heart Association in its journal Circulation: Genomic and Precision Medicine.

The longer the duration of these cancer therapies, the higher the risk of cardiovascular disease, which also increases with age.

"The statement provides data on the risks of each type of hormonal therapy so clinicians can use it as a guide to help manage cardiovascular risks during cancer treatment," Dr. Tochi M. Okwuosa, chair of the statement writing group, said in a news release. Tochi is director of cardio-oncology services at Rush University Medical Center in Chicago.

Hormone-dependent cancers, such as prostate and breast cancers, are the most common cancers in the United States and worldwide, not including skin cancers. As improvements in treatment – including increased use of hormone therapies – allow people to live longer, cardiovascular disease has emerged as a leading cause of illness and death in these cancer survivors.

There are currently no definitive guidelines for monitoring and managing hormone therapy-related heart risks. The statement calls for clinicians to be alert for worsening heart problems in those with prior heart disease or risk factors. It also says even those without pre-existing heart problems are at higher risk because of their exposure to hormone therapy.

The statement recommends a team-based approach for treating people receiving these therapies that includes the oncology team, cardiologist, primary care doctor, dietitian, endocrinologist and other health care professionals as needed.

"For patients who have two or more cardiovascular risk factors, it is likely that referral to a cardiologist would be appropriate prior to beginning hormone treatment. For patients already receiving hormonal therapies, a discussion with the oncology team can help to determine if a cardiology referral is recommended," Okwuosa said.

Specifically, the committee's review concluded that tamoxifen, used to treat breast cancer, increases the risk of blood clots, while aromatase inhibitors increase the risk of heart attack and stroke more than tamoxifen. For breast cancers that develop resistance to the initial medication, using more than one type of hormone therapy can improve cancer outcomes. But treatment with multiple hormones is associated with higher rates of cardiovascular conditions such as high blood pressure, abnormal heart rhythms and blood clots.

Androgen deprivation therapy, which reduces testosterone and is used to treat prostate cancer, increases cholesterol and triglyceride levels, adds body fat while decreasing muscle and impairs the body's ability to process glucose, which may result in Type 2 diabetes, the statement concluded. These metabolic changes are associated with a greater risk of heart attacks, strokes, heart failure and cardiovascular death.

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