New research warns that, after completing breast cancer treatment, women aged 45 and over have a heightened risk of developing cardiovascular disease.

According to the World Health Organization (WHO), breast cancer is the most common form of cancer that doctors diagnose among women across all the world's populations. At the same time, however, it is also one of the most treatable forms of cancer, with a 5-year relative survival rate of 91% among white women, and a 78% survival rate among black women—and these rates are increasing.

Yet although life expectancy is on the rise for females who undergo breast cancer treatment, they, nevertheless, face a number of health risks in the aftermath of therapy. Late side effects can include damage to the bones, premature menopause symptoms, and poor heart health.

A new study from the Botucatu Medical School at Paulista State University in Sao Paulo, Brazil, confirms that women of more than 45 years of age who have undergone breast cancer treatment have a heightened risk of developing cardiovascular problems.

The study's findings—which appear online ahead of print in the journal Menopause of the North American Menopause Society (NAMS)—also explain why women who have experienced breast cancer are more at risk of heart disease.

"In addition to toxicity from chemotherapy or radiation therapy, many women go on anti-estrogens if they have an estrogen-sensitive breast cancer. Loss of estrogen may be associated with higher risk of heart disease," Dr. JoAnn Pinkerton, the executive director of NAMS—although not involved in the current study—explained for Medical News Today.

What increases heart disease risk?

In the study, first author Dr. Daniel de Araujo Brito Buttros and colleagues worked with 288 female participants. Of these, 96 had successfully completed breast cancer treatment, while 192 were completely healthy and had never experienced breast cancer. All the women were 45 years old and over and had gone through menopause. None of them had established cardiovascular disease.

The researchers' analysis revealed that, when compared with women over 45 who never experienced breast cancer, those who had received breast cancer treatment had a much higher likelihood of having metabolic syndrome, diabetes, atherosclerosis, and hypertriglyceridemia (elevated blood levels of fatty molecules), as well as abdominal obesity.

All of these conditions are top risk factors for developing cardiovascular disease. Moreover, these women's risk of cardiovascular, event-related death was increased, matching death rates that experts associate with a breast cancer diagnosis.

"About 1 in 8 women (about 12%) [in the United States] will develop invasive breast cancer over the course of their lives. In 2019, an estimated 268,600 new cases of invasive breast cancer are expected to be diagnosed in women in the United States, along with 62,930 new cases of noninvasive (in situ) breast cancer," Dr. Pinkerton told MNT.

"As of January 2019, there are more than 3.1 million women with a history of breast cancer in the United Statges. This includes women currently being treated and women who have finished treatment," she continued. Since so many women are likely to receive breast cancer treatment, it is important that they speak to their doctors to receive advice about any late side effects or health risks, so that they can take adequate measures to prevent these."

"Heart-healthy lifestyle modifications can decrease both the risk of recurrent breast cancer and the risk of developing heart disease. Thus women should be evaluated for heart disease risk, as they are being treated for breast cancer, and continue to be followed for increased risk after treatment for breast cancer."

—Dr. JoAnn Pinkerton, executive director of NAMS