Breast cancer patients with a history of heart disease are more likely to have advanced tumors at the time of diagnosis, a new study suggests.
“There is growing evidence that cardiovascular disease, in particular cardiovascular events like a heart attack, leads to a suppressed immune system,” says the senior study author, Kevin Nead, MD, an assistant professor of epidemiology and radiation oncology at the University of Texas MD Anderson Cancer Center in Houston.
“When the immune system is suppressed, it may be less effective at doing its job to prevent the development, growth, and spread of cancer,” Dr. Nead adds.
The Connection Between Heart Disease and Breast Cancer
The link between heart disease and breast cancer progression in the study appeared to involve the most common type of breast cancer, so-called hormone receptor–positive (HR+) tumors, which are fueled by hormones like estrogen and progesterone. People with advanced HR+ breast cancer were 11 percent more likely to have heart disease than individuals with early-stage HR+ breast cancer.
The study found that people with locally advanced breast cancer — meaning tumors had spread into surrounding tissue and lymph nodes but not to distant parts of the body — were 9 percent more likely to have cardiovascular disease.
It also found that people with metastatic breast cancer — meaning tumors had spread to distant parts of the body — were 20 percent more likely to have cardiovascular disease.
Breast Cancer and Heart Disease May Have Common Underlying Factors
The study wasn’t a controlled experiment designed to prove whether or how heart disease might directly cause or accelerate the progression of breast cancer.
It’s possible, however, that cardiovascular disease and breast cancer may share some root causes, says Alexandra Thomas, MD, an oncologist at the Duke Cancer Institute in Durham, North Carolina, who wasn’t involved in the new study.
Like Nead, she notes that immune suppression from heart disease might cause cancer to grow faster. “Or inflammation from the cancer might cause heart damage, such as the development of plaques in the coronary arteries,” Dr. Thomas says.
One limitation of the study is that participants were predominantly white, and it’s possible that outcomes might differ for people from other racial or ethnic groups. The study also didn’t look at women younger than 65.
Heart Healthy Habits May Protect Against Some Cancers
Study results add to the evidence that lifestyle choices known to protect the heart may have additional disease-prevention benefits.
“A heart-healthy lifestyle can help prevent breast cancer and contribute to less-advanced disease at diagnosis, which ultimately may have a greater chance of cure,” Nead says. “The results of our study also suggest that women with cardiovascular disease could benefit from initiating breast cancer screening earlier or undergoing more frequent mammograms.”
Regular exercise, a heart-healthy diet, and avoidance of smoking and significant stress are among the lifestyle choices that can reduce the risk of breast cancer, says Daniel Addison, MD, an associate professor, cardiologist, and the director of the cardio-oncology program at the Ohio State University Wexner Medical Center in Columbus.
“Controlling heart disease is another opportunity to lower cancer risk,” says Dr. Addison, who wasn’t involved in the new study. “Periodic screening for heart disease, especially after intense cancer treatment, may also help prevent or control heart disease in cancer patients.”
