Newer Breast Cancer Drugs Increase Heart Risks

<"">Aromasin by Pfizer Inc., Arimidex by AstraZeneca, and Femara by Novartis AG, all breast cancer drugs in a class known as aromatase inhibitors and all drugs that stop estrogen production, have been linked to a significant increase in risks for developing heart disease, said

Estrogen is the hormone that prompts cancer cell growth and most breast cancers—about 2/3rd—say the National Institutes of Health (NIH), are fed by the hormone.

The breast cancer medications have been found to make women 26 percent likelier to develop heart diseases versus older therapy, according to a study trial just presented at the San Antonio Breast Cancer Symposium in Texas, wrote Bloomberg. The study suggests that those women who are at an increased risk for cardiac conditions limit the use of these therapies; Tamoxifen, a generic alternative that was approved in 1977, has less risks for those complications, wrote Bloomberg, citing the study.

“It appears that aromatase inhibitors have a significant increase in cardiotoxic side effects, such as heart attack, angina, and heart failure,” said Eitan Amir, a senior fellow in oncology and hematology at the Princess Margaret Hospital in Toronto, in a statement. “Switching drugs may reduce the side effects,” quoted Bloomberg.

But, tamoxifen is not without its problems in certain patients. In 2006, a panel to the U.S. Food and Drug Administration (FDA) found that in some patients with estrogen-related breast cancer, there was a risk of recurrence and poor responsiveness to Tamoxifen. Scientists believe the risk of recurrence concerns poor enzyme activity in certain women. For women with deficiencies with the enzyme CYP2D6, which is required to metabolize the drug so that it can perform its intended goal of estrogen reduction, tamoxifen has been proven to be less effective. When this was discovered, aromatase inhibitors, believed to be more successful in the treatment and prevention of the disease, were heavily touted.

Over 7,500 postmenopausal women with early breast cancer participated in the recent study, said Bloomberg, which was funded in the United States by the National Cancer Institute and, in Europe, by the International Breast Cancer Study Group.

Research revealed that women taking aromatase inhibitors experienced both a 26 percent increased likelihood of developing cardiac disease and a 47 percent increased likelihood of fracture, versus those taking tamoxifen, regardless of how long they were treated, according to a review of seven studies originally used to gain approval of the drug, noted Bloomberg. Those taking tamoxifen were likelier to develop endometrial cancer and significant leg blood clots.

A second, emerging study found that Aromasin worked as well as Arimidex, following the first “head-to-head” comparison of the two, said Bloomberg. Those on Aromasin did exhibit increased rates for mood changes and liver function reductions, but were less likely to develop osteoporosis and elevated cholesterol levels, said Bloomberg.

Heart disease is the leading cause of women’s death, claiming about 433,000 lives annually, according to the American Heart Association, wrote Bloomberg. This year alone, about 209,000 women will be diagnosed with breast cancer—over 40,000 will die—making breast cancer the most common tumor type in women, notes the American Cancer Society.

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