Cardiovascular disease – the leading cause of death in U.S. women – and breast cancer are the top two women’s health concerns, excluding skin cancer. Cardiovascular disease and breast cancer don’t exist in silos – patients may be surprised to learn of the links between these diseases. Understanding these connections is especially important for breast cancer survivors. Recent research finds that these individuals have higher risks for certain cardiometabolic risk factors that can increase their risks for heart and vascular disease.
Cardiometabolic Risk Factors, Cardiometabolic Syndrome, and Cancer
Current estimates suggest that as many as 25% of adults have cardiometabolic syndrome, a cluster of risk factors, including:
- Abdominal obesity
- Dyslipidemia (unhealthy or imbalanced total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides levels)
- Elevated fasting blood sugar
Cardiometabolic risk factors elevate an individual’s risk for cardiovascular disease, including coronary artery disease, heart attack, and stroke. Many physicians, particularly those in primary care, focus on helping patients manage their risk factors to prevent those diseases. However, it’s becoming increasingly evident that cardiometabolic syndrome impacts cancer risk.
“Research has found associations between cardiometabolic syndrome and cancers of the bladder, breast, colon and rectum, liver, and endometrium,” said Dr. Jocelyn De Yao, medical oncologist and hematologist at Rocky Mountain Breast Specialists (RMBS). “Lifestyle factors can play a role in the development of cardiometabolic risk factors and cardiometabolic syndrome. In addition, breast cancer and heart disease share certain risk factors, and taking particular heart-healthy steps, such as exercising regularly and following a healthy diet, may help protect against both.”
A sedentary lifestyle can increase individuals’ risk for cardiometabolic risk factors, including obesity and hypertension. The same is true of an unhealthy diet. Consequently, counseling breast cancer survivors about the importance of adopting healthy lifestyle modifications is key.
How Cardiovascular Disease Affects Breast Cancer Patients and Survivors
In recent years, clinicians have gained a better understanding of the ways in which breast cancer and cardiovascular disease converge. One of the main links between them is breast cancer treatment, which, in some patients, can lead to heart problems soon after treatment concludes or in later years, according to the American Heart Association. For example, radiation therapy can cause arterial blockages and arrhythmias. Chemotherapy may cause hypertension, blood clots, or weakening of the heart.
Cardiovascular disease and breast cancer can occur concurrently. In some cases, heart disease can complicate or delay breast cancer treatment. Rarely, cancer itself can lead to cardiac issues.
Once treatment for breast cancer concludes, heart disease remains a major concern during survivorship. Many breast cancer survivors and their clinicians are understandably concerned about cancer recurrence. However, for many patients, cardiovascular disease is a bigger threat. The American Heart Association reports that, as more women survive breast cancer, more are at risk for long-term cardiac issues due to complications of treatment. Among older women who’ve had breast cancer, cardiovascular disease is more likely to cause mortality than a recurrence of cancer.
Researchers and clinicians are learning more about the effects of cardiometabolic risk factors on women with breast cancer and breast cancer survivors. Recent studies have made clear that education about these risk factors is crucial.
Cardiometabolic Risk Factors and Mortality
In a 2018 study published in the journal Cancer, a multicenter group of researchers examined how cardiovascular risk factors in women with breast cancer might affect death from breast cancer, cardiovascular disease, and other causes. Using data from the Women’s Health Initiative, the study included 8,641 women with local or regional invasive breast cancer. The majority of the women had at least two cardiometabolic risk factors, such as high waist circumference, hypertension, high cholesterol, or Type 2 diabetes.
Follow-up occurred for a median of 11.3 years. During that time, 2,181 of the participants died, with 28.4% of the deaths due to breast cancer. The researchers found that having a higher number of cardiometabolic risk factors correlated to a higher risk of death due to cardiovascular disease or other causes. However, the presence of many cardiometabolic risk factors did not lead to a higher risk of mortality from breast cancer.
The Incidence of Cardiometabolic Risk Factors Among Breast Cancer Survivors
A 2022 study in the Journal of Clinical Oncology sought to answer this question. Researchers identified 14,942 cases of invasive breast cancer that occurred at Kaiser Permanente Northern California from 2005 to 2013. After matching the cases of breast cancer to women without the disease in a 1:5 ratio (for a total of 74,702 control patients), the team estimated cumulative incidence rates of dyslipidemia, hypertension, and diabetes.
The study found that women with breast cancer had a higher rate of hypertension than women in the control group, 10.9% to 8.9%. The rate of diabetes was also higher in the breast cancer group (2.1% to 1.7%) and remained so a decade later. Left-sided radiation therapy and endocrine therapy were associated with a higher hypertension risk. Those therapies, as well as chemotherapy, were linked with a higher risk of diabetes.
Interestingly, women who had breast cancer and were of normal weight – a body mass index less than 24.9 – at diagnosis were more likely to develop diabetes and high blood pressure. In an interview with Oncology Times, lead study author Marilyn Kwan, Ph.D., Research Scientist III at the Division of Research of Kaiser Permanente Northern California, noted that the reason for higher risk levels among normal-weight women was unclear.
Important Education for All Breast Cancer Survivors
Breast cancer isn’t monolithic. It encompasses many types with varying hormone receptor statuses. It ranges from disease confined to a single duct to metastatic breast cancer. It includes common types, such as invasive ductal carcinoma and inflammatory breast cancer, to rarer, difficult-to-treat forms, such as triple-negative breast cancer. Making patients aware of cardiometabolic risk factors should be a key part of survivorship care, regardless of breast cancer type or hormone receptor status.
“Oncologists and primary care providers should discuss the threat of cardiometabolic risk factors with their patients who are breast cancer survivors,” Dr. De Yao said. “Breast cancer survivors need to know that cardiovascular disease poses a risk to their health after cancer, but there are a variety of steps they can take that can help mitigate the risk.”
Home to medical and radiation oncologists specializing in breast cancer, and with locations in communities throughout the state, RMBS treats the most adult cancer patients in Colorado. Refer a patient.