The risk of breast cancer coming back (recurrence) and death due to breast cancer increased in people who had a heart attack, stroke, or heart failure after being treated for early-stage breast cancer, according to a study.
The research was published in the July 13, 2020, issue of Nature Medicine. Read the abstract of “Myocardial infarction accelerates breast cancer via innate immune reprogramming.”
Breast cancer and heart problems
A number of studies have shown that women treated for breast cancer have a higher risk of heart problems compared to women who haven’t been treated for breast cancer. Treatments such as anthracycline chemotherapy medicines, radiation, and targeted therapies, including Herceptin, have been shown to affect the heart, blood vessels, and immune system, which can increase the risk of heart attack, stroke, and heart failure.
Still, it wasn’t clear if having heart problems after breast cancer treatment could affect breast cancer outcomes, which is why the researchers did this study.
About the study
The study had two parts. In the first part, the researchers looked at breast cancer cells implanted in mice to see how a surgically induced heart attack affected the cells. The researchers found that compared to breast cancer cells that had not been exposed to a heart attack, the exposed breast cancer cells grew twice as fast and there were twice as many cancer cells.
The researchers looked to see why this might be happening. They found that a heart attack led to an increase in a type of immune system cell called a Ly6Chi monocyte. A monocyte is a type of white blood cell that fights infection and helps other white blood cells destroy cancer cells.
The researchers found that in addition to increasing the number of Ly6Chi monocytes, being exposed to a heart attack also reprogrammed the Ly6Chi monocytes, reversing their function. So instead of helping the immune system by destroying cancer cells, the Ly6Chi monocytes were now suppressing the immune system. When the reprogrammed Ly6Chi monocytes went into a cancer cell, the cancer cells grew and multiplied faster.
The researchers also found that having a heart attack altered the expression of 235 genes in immune system cells. When a gene’s expression is changed, it changes the way the gene functions. In particular, genes involved in stopping the development of cancer cells were suppressed. This means that it was likely much easier for cancer cells to grow and multiply.
"We think that heart attack is somehow causing this epigenetic reprogramming across the genome," said study co-author Kathryn Moore, Ph.D., Jean and David Blechman Professor of Cardiology at the New York University School of Medicine, in an interview.
In the second part of the study, the researchers looked at health information from 1,724 people diagnosed with early-stage breast cancer. None of the people had preexisting heart problems or risk factors for heart problems.
The average time since breast cancer diagnosis was 11.7 years.
Of the 1,724 people in the study, 270 had some type of heart problem in the years after being diagnosed with breast cancer. Compared to people who did not have heart problems after breast cancer diagnosis, people who had a heart attack, stroke, or heart failure were 59% more likely to have a cancer recurrence.
The researchers also looked to see whether having heart problems affected a person’s risk of dying from breast cancer. Of the 1,544 people included in that analysis, 168 had some type of heart problem in the years after being diagnosed with breast cancer. Compared to people who did not have heart problems after a breast cancer diagnosis, people who had a heart attack, stroke, or heart failure were 60% more likely to die from breast cancer.
"I think one of the most important things for breast cancer survivors to understand is that there is this link between breast cancer and heart disease and that they are at increased risk for heart disease after surviving breast cancer," Moore said in an interview. "After surviving breast cancer, they should speak with their healthcare providers about closely monitoring for cardiovascular risk factors."
What this means for you
While the results of this study are very concerning, they do emphasize how important it is to have a survivorship care plan.
Because of treatments they’ve received, many breast cancer survivors have a higher risk of developing other diseases as they age, including high blood pressure, heart disease, and osteoporosis. To make sure breast cancer survivors are regularly screened for these and other diseases they may be at higher risk for, experts developed the idea of survivorship care planning. The plan is a document that outlines your specific healthcare needs and concerns, as well as which doctors to see.
After your main breast cancer treatment is done, it’s important to focus on what’s now most important: your good health. You have to make sure you get the best ongoing care and live your best life. If you’ve finished breast cancer treatment and your oncologist hasn’t talked to you about a survivorship care plan, it’s a good idea to bring it up at your next appointment. Here are some questions you may want to ask your oncologist:
- Can I get a survivorship care plan in writing that explains all the medical issues I need to consider and tells me which screening tests I need and when I should have them?
- Which doctor should I see for each medical issue?
- If your oncologist recommends that you see a specialist — a cardiologist for example — and you’ve never seen one before, you may want to ask for a referral to a specific doctor.
- If there is anything in your survivorship care plan that you don’t understand, ask your doctor or nurse to explain it.
You also may want to talk to your oncologist about this study and make sure that regular checks for heart disease are in your survivorship care plan.
It’s also a good idea to talk to your primary care doctor about your survivorship care plan and ask which parts of it she or he will be responsible for.
There’s only one of you and you deserve the best care possible, both during and after cancer treatment. Because the idea of survivorship care plans is relatively new, you may have to advocate for yourself to make sure that you get a written plan.
Written by: Jamie DePolo, senior editor
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