Heart Disease and Breast Cancer

Diana Zuckerman PhD and Danielle Shapiro, MD, MPH, Cancer Prevention and Treatment Fund

In a first-of-its-kind scientific statement, the American Heart Association reminds women that heart disease is the #1 killer of women and that frequently used breast cancer treatments can increase a woman’s chances of developing heart disease.  These treatments include radiation, hormone therapy, chemotherapy, and targeted therapy.

Facts that will Help you Decide your Treatment Options

Fact:  Heart disease affects almost 50 million U.S. women, and 1 in 3 deaths in women in the U.S. are due to heart disease. Breast cancer affects about 3.3 million U.S. women, and 1 in 32 deaths in women are due to breast cancer.  That means that women are about 10 times more likely to die of heart disease than to die of breast cancer.

 Fact: Women with a history of breast cancer are more likely to die from heart disease than women without a history of breast cancer.  That is because some health habits cause both heart disease and breast cancer, and because some breast cancer treatments can also increase your chances of dying of heart disease.

Fact: There are many things you can do to decrease your risks of developing both breast cancer and heart disease:  not smoking, eating a healthy diet, losing weight (if you are overweight or obese) and being physically active

Which Breast Cancer Treatments Harm the Heart?

Radiation therapy:

Radiation therapy is often recommended for women who have a lumpectomy, so it is important to know that it can cause inflammation that can damage heart muscles and blood vessels. Studies on animals show that it can also cause clots to form in the coronary arteries. The risks are higher for radiation that is directed at the left side of the chest. The effects are not immediate, but radiation can increase the chances of heart disease at any time between 5-30 years after radiation therapy.

Hormonal therapy:

Tamoxifen is a hormone therapy that is often prescribed for breast cancers that are sensitive to the hormone estrogen. Studies show that tamoxifen lowers bad cholesterol, but there is no evidence this decreased their chances of developing heart disease or dying from it. Perhaps that is because tamoxifen also increases the chances of forming blood clots, which can be dangerous if they are in the lungs, heart, or brain.

Aromatase inhibitors are a type of hormone therapy that is often prescribed for postmenopausal women with breast cancers that are sensitive to the hormone estrogen. Aromatase inhibitors increased the chances of developing heart disease by less than 1%, but the risks may be higher (about 7%) in women who already have heart disease. The U.S. Food and Drug Administration issued a warning about this for one aromatase inhibitor, anastrazole (brand name arimidex).

Chemotherapy:

Doxorubicin, a type of anthracycline-based chemotherapy, can have harmful effects on the heart, which can be permanent and irreversible. Doxorubicin can damage heart cells and cause inflammation that can weaken the heart muscles, which can lead to heart failure. Heart failure means the heart isn’t pumping well, which can cause the body to become swollen and the lungs to fill with fluid.  This can cause you to feel short of breath, tired, or weak.

5-Fluorouracil (5-FU), is a type of antimetabolite chemotherapy used for metastatic breast cancer and other cancers. Some women who take 5-FU develop chest pain caused by a blood clot or tightening in the blood vessels that feed the heart (coronary arteries). In very rare cases, the heart does not get enough blood, which can cause a heart attack.

Targeted Drugs:

Trastuzumab or pertuzumab are targeted drugs that work against breast cancer cells that make the protein HER2. These medications can cause heart failure that is reversible. Because of the risks, women should only take these medications for 1 year.  Women who are over age 50 with diagnosed heart disease, high blood pressure, reduced heart function, or prior use of doxorubicin are most likely to be harmed by this drug.

Prevention

Studies show that there are things you can change to help prevent breast cancer and heart disease.

  1. Stop smoking
  • For heart health – Smoking increases the chances of having a heart attack or stroke.
  • For breast health – Women who start smoking at a younger age, and smoke for many years, are more likely to develop breast cancer. Smoking causes about 4 in 1000 breast cancers. Quitting decreases the chances of developing breast cancer, but it may take about 20 years to see the full benefits. To read more, click here.
  1. Maintain a healthy weight
  • For heart health – Being overweight or obese (a BMI of 25 or above) increases the chances of developing heart disease.
  • For breast health – Every extra 10 pounds over “normal” weight (BMI below 25) increases the chance of developing breast cancer by about 10%.
  1. Be physically active
  • For heart health – Sitting, watching TV, lying in bed, or driving for 10 hours or more a day while you are awake instead of 5 hours or less per day increases the chances of developing heart disease by about 18%. The AHA recommends exercising for 30 minutes or more a day 5 days each week.
  • For breast health – Those same sedentary activities for 12 hours or more a day compared to 5.5 hours or less increase the chance of developing breast cancer by about 80%. To prevent breast cancer, exercise for 30 minutes or more a day 5 days each week.
  1. Eat a healthy diet
  • For heart health – Eating a diet rich in fresh vegetables, Fresh fruit, fish, poultry, and whole grains reduces your chance of dying from heart disease by about 28% compared to eating a typical U.S. diet with many fast foods, red meats/processed meats, and packaged or processed foods.
  • For breast health – The typical U.S. diet is associated with a greater chance of developing breast cancer, but the clearest evidence is for eating at least 15 oz of red meat or processed meat each week compared to less than 9 oz. of red meat or processed meat.

Heart Health for Breast Cancer Patients and Survivors

High blood pressure, diabetes and high cholesterol increase the chances of having a heart attack or dying from one. The AHA recommends controlling blood pressure, blood sugar, and blood cholesterol with diet, exercise, and medications when needed. Exercise is good for the heart and it also fights off cancer. Studies show that exercising 30 minutes a day for 5 days out of the week decrease the chances of breast cancer returning and from dying from breast cancer.

The Bottom Line

Heart disease is a major cause of deaths in women, and remains a number one cause of death in breast cancer survivors. Women who are at a higher risk of heart disease should talk with their doctors about the risks and benefits of commonly used cancer treatments.

All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.

References:

Laxmi S. Mehta. et al. Cardiovascular Disease and Breast Cancer: Where These Entities Intersect: A Scientific Statement From the American Heart Association. Circulation. 2018, originally published February 1, 2018. https://doi.org/10.1161/CIR.0000000000000556

Jones ME. et al. Smoking and risk of breast cancer in the Generations Study cohort. Breast Cancer Research. 2017;19:118. https://doi.org/10.1186/s13058-017-0908-4