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For Release: October 23, 2000
Radiation Therapy is Not Associated with Increased Risk of Heart Damage
Women diagnosed with breast cancer on their left side needn't worry that post-lumpectomy radiation therapy will damage their heart, a new study reveals.
An examination of 2,128 breast cancer patients registered at a Toronto hospital between 1982 and 1988 found that radiation therapy performed on the left breast following breast-conserving surgery did not increase a patient's risk for a heart attack.
"Whenever the left breast is treated, a small part of the heart receives some radiation," explained Katherine Vallis, M.D., of Princess Margaret Hospital in Toronto, Ontario. "There was concern that as a result, the radiation might cause subtle damage to the heart therefore increasing the risk for heart attack in women," she added.
Older studies suggested that women who received radiation therapy following a mastectomy were at higher risk of heart attack compared to those who didn't receive radiotherapy. Researchers had questioned whether modern medical techniques, such as post-lumpectomy radiation therapy, would yield similar results.
Two groups of patients were studied - 1,074 women had received treatment for left-sided breast cancer and 1,054 for right-sided cancer. All had early-stage, or operable, breast cancer, and all had a lumpectomy followed by radiation therapy.
The survival rate for the whole group after five years was 81 percent; after 10 years, it was 67 percent. According to Dr. Vallis, the rates are typical of what would be expected in women with early-stage breast cancer.
Revealingly, the study showed the risk of fatal and non-fatal myocardial infarction, or heart attack, to be nearly the same.
Of those women with left-sided breast cancer, eight suffered fatal myocardial infarctions (MI), while 18 experienced non-fatal MIs. Of those with right-sided breast cancer, six suffered fatal MIs, while 17 experienced non-fatal MIs.
Dr. Vallis pointed out that these rates are very similar to those found among women of the same age in the general population, demonstrating that patients treated with post-lumpectomy radiation therapy are at no greater risk for a heart attack.
"We can say conclusively from this study of a large group of patients, that using these modern techniques, we haven't found any increased risk for heart attack even many years later," said Dr. Vallis. "And if there is an effect, it must be a small one because we haven't been able to detect it."
The study was presented October 23 at the American Society for Therapeutic Radiology and Oncology annual meeting in Boston, MA.