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A new study looked at what happened years after a breast cancer diagnosis. Getty Images
  • In a new study, they found women diagnosed with breast cancer are more likely to die of heart disease than any other cause of death, other than cancer itself.
  • Heart disease remains the number one cause of death for women.
  • Experts say this shows how physicians need to help patients even after their cancer goes into remission.

Breast cancer is one of the most common causes of cancer-related deaths among women in the United States. In 2019, an estimated 41,760 women in the country will die from the disease.

But thanks to improvements in detection and treatment, survival rates for women with breast cancer have significantly improved in recent decades.

Now, a new study reports that a significant number of people diagnosed with breast cancer will live so long they’re more likely to die of another disease, especially heart disease.

According to the study of women diagnosed with breast cancer between 2000 and 2015, most of the women who survived for 10 years or longer after their breast cancer diagnosis died from non-cancer causes.

The study was published today in the medical journal Cancer.

Besides cancer itself, heart disease was the most common cause of death among women who were diagnosed with breast cancer.

Within 10 years of being diagnosed, the most common cause of death was heart disease, followed by cerebrovascular disease (such as a stroke or blood clot). After 10 years, the most common non-cancer cause of death was heart disease and Alzheimer’s disease.

“Non-cancer diseases, such as heart diseases, contribute to a significant number of deaths in patients with breast cancer, even higher than in the general population,” the senior author of the new study, Dr. Mohamad Bassam Sonbol, said in a statement.

“Cancers other than breast cancer are also an important cause of death in patients with a history of breast cancer,” Dr. Sonbol added.

In order to understand what happens to women after a breast cancer diagnosis, Dr. Sonbol and colleagues analyzed data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program (SEER).

This program collects data on cancer incidence and survival rates from population-based cancer registries that cover more than a quarter of the country’s population.

“The problem with SEER database studies is that it’s not necessarily representative of the whole population in the United States,” Dr. Sarah Cate, a breast cancer specialist and assistant professor of surgery at Icahn School of Medicine at Mount Sinai, told Healthline.

“But it is interesting to see what these patients ended up dying from,” she continued.

The authors of the study analyzed the records of 754,270 women who were diagnosed with breast cancer between 2000 and 2015. Among those women, 24.3 percent died by the end of 2015.

Among the women who died within 5 years of their breast cancer diagnosis, most died from breast cancer or a different type of cancer. But the longer women survived beyond their diagnosis, the less likely they were to die from cancer.

In women who died 5 to 10 years after being diagnosed with breast cancer, roughly half died from non-cancer causes.

In women who died more than 10 years following their breast cancer diagnosis, more than 60 percent died from non-cancer causes.

Heart disease was the most common non-cancer cause of death in breast cancer patients and survivors.

Cerebrovascular diseases and Alzheimer’s disease also accounted for significant proportions of non-cancer deaths.

“The findings should not be surprising because the non-cancer causes of death that were seen are the same common causes of death that affect the population as a whole,” Dr. Elizabeth Klodas, a cardiologist in Minneapolis, Minnesota, and founder of Step One Foods, told Healthline.

Heart disease is the number one killer of American women.

And compared to the general population, this study found that breast cancer patients who survived for more than 10 years after their cancer diagnosis were even more likely than average to die from heart disease.

“It is a wake-up call that we can’t just focus on breast cancer treatment and follow-up in women diagnosed with this disease,” Dr. Klodas said.

“As part of optimal care, we have to attend to the whole person and address any and all risk factors for other health issues,” she continued, “especially cardiovascular disease.”

Although more research is needed to understand the links between breast cancer and heart disease, certain breast cancer treatments may play a role.

“Some chemotherapy agents are directly toxic to heart muscle, some increase propensity of the blood to clot, and some cause cholesterol levels to rise,” Dr. Klodas explained.

Some breast cancer treatments can also lead to weight gain, causing body mass index (BMI) to rise. The psychosocial effects of breast cancer diagnosis and treatment can also disrupt people’s exercise routines and other daily habits, which may contribute to weight gain as well, Dr. Cate said.

In turn, people with overweight or obesity are at increased risk of heart disease. Higher BMI is also associated with higher risk of breast cancer recurrence.

To help manage the risk of heart disease and breast cancer recurrence, Dr. Cate emphasized the importance of getting regular exercise and eating a well-balanced diet.

“I think the most important thing is to focus on what we can modify,” Dr. Cate said, “and diet and exercise are two of the most important things for people to modify, especially with a breast cancer diagnosis or after treatment for breast cancer.”

To monitor and manage your risk factors for heart disease, getting regular heart-health screening tests may also help.

If your weight, blood cholesterol, blood pressure, or blood sugar levels rise outside of recommended ranges, your doctor may prescribe lifestyle changes, medications, or other treatments to lower them.

“Make sure all of your numbers — cholesterol, blood pressure, blood sugar, weight — are as optimized as possible, and if you smoke, quit.” Dr. Klodas advised.

“Finally, take new or unexplained chest pain, shortness of breath, or unusual fatigue seriously,” she continued. “These could be symptoms of a heart problem.”