TUESDAY, Dec. 27 (HealthDay News) -- Women who have breast
cancer on the left side of the body and who are treated with
radiation therapy have a higher risk of developing narrowing of the
arteries that lead to the heart, researchers say.
A new Swedish study found that the risk of having moderately
narrowed coronary arteries was more than four times greater for
women who had left-sided breast cancers treated with radiation
compared to right-sided breast cancers treated with radiation. The
odds were seven times higher for more severe narrowing on the left
side versus the right, according to the study published in the Dec.
27 online edition of the
Journal of Clinical Oncology.
"We suggest that the coronary arteries be regarded as organs at risk in radiation therapy, and that every effort be made to avoid radiation dose to the coronary arteries," wrote study authors led by Dr. Greger Nilsson, of the department of oncology, radiology and clinical immunology at Uppsala University Hospital.
However, it's also important to note that of a group of 8,190
women who had breast cancer, just 199 had to be referred for
coronary angiography (a treatment for blocked blood vessels).
"Women need to be aware that there is a risk, but the overall risk is still relatively small, and the benefits of radiation in the treatment of breast cancer still outweigh the risks," said Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York City.
Cancer treatments, such as radiation and chemotherapy, are
designed to destroy cancer cells. Unfortunately, healthy cells are
often damaged, too. Treatment techniques are constantly being
refined, and today's treatments target fewer healthy cells than
treatments from years past.
For example, newer radiation techniques help protect the heart
and the arteries leading to it, according to Dr. Timothy Zagar, an
assistant professor in radiation oncology at the University of
North Carolina at Chapel Hill. One such technique is to give bursts
of radiation only when a patient is taking a deep breath. During a
deep breath, the main artery going to the heart separates from the
breast and chest wall, which keeps it away from the radiation.
Zagar, co-author of an accompanying editorial in the same issue
of the journal, said researchers don't know exactly how radiation
causes damage to coronary arteries, but it's believed to damage the
cells lining the arteries (endothelial cells), which causes
inflammation, which can lead to hardening of the arteries.
The current study included women from Sweden who were diagnosed
with breast cancer between 1970 and 2003. Of the 8,190 women, the
researchers found 199 women who had undergone coronary angiography,
suggesting significant coronary artery disease.
Coronary artery narrowing (stenosis) is graded on a scale of
zero to 5. Zero indicates a healthy blood vessel, while 5 indicates
a blocked blood vessel.
When the researchers compared women who'd had radiation
treatment on the left side of their body versus the right, they
found that the odds of a grade 3 to grade 5 stenosis in a
left-sided artery were 4.38 times higher. The odds of a grade 4 or
grade 5 stenosis were 7.22 times higher for women who had
left-sided breast cancer.
In women who received radiation in high-risk areas near the
heart's arteries, the risk of a grade 3 to grade 5 stenosis was
nearly twice as high as it was in women who had radiation in
low-risk areas, or who didn't have radiation.
Zagar pointed out that this study was done over a long period of
time and that changes in the way radiation is delivered would
likely result in lower odds of coronary artery stenosis for women
treated with radiation today.
In addition, Zagar said, "I don't think this study's findings
would justify changing from a lumpectomy [breast-conserving
surgery] to a mastectomy [surgical removal of the breast].
Breast-conserving therapy is very important to many women, and the
number of coronary events are still low," he added.
"It's important to understand that with all treatments, there are risks," Bernik said. "And, we know that this is one of the risks with radiation of left-sided breast cancer. Women need to keep in mind that they're at increased risk of coronary events and need to follow up with their doctor going forward."
Learn more about radiation treatment for cancer from the
U.S. National Cancer Institute.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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