Radiation Therapy For
Breast Cancer May
Damage The Heart

NEW YORK (Reuters Health) - Treatment with radiation can help prevent breast cancer from returning, but for older women and those who have a low risk of a relapse, the risks of radiation may outweigh its benefits in the long run, researchers report.
Even though radiation can reduce the risk of dying from breast cancer, it may increase the risk of dying from other causes, particularly heart disease, results of a study suggest.
Radiation has been shown to prevent breast cancer from returning in the short term, but the long-term benefits of the treatment have been less clear, according to a team of researchers led by Dr. Rory Collins, from the Clinical Trials Services Unit at Radcliffe Infirmary in Oxford, England. To see whether women who undergo radiation fare better decades after treatment, the researchers reviewed 40 studies that followed nearly 20,000 women.
Overall, radiation prevented breast cancer from returning in about two thirds of the women, Collins told Reuters Health in an interview. When the results of all studies were combined, radiation did not improve the death rate from breast cancer during the first 2 years after treatment, but afterwards, women who underwent radiation were about 13% less likely to die from breast cancer each year than women who did not have the treatment. The findings are published in the May 20th issue of The Lancet.
But the benefits of radiation came with a cost, the authors note. The death rate from causes other than breast cancer was actually higher in women who underwent radiation. Beginning 2 years after treatment, the annual rate of deaths not related to breast cancer was about 21% higher in women treated with radiation. According to Collins, most of this increased risk was heart-related, probably caused by radiation damage to the heart and arteries.
Overall, the 20-year survival rate was about 1% higher in women treated with radiation, 37.1% versus 35.9%.
In the interview, Collins said that the benefits and costs of radiation varied among different groups of women. Referring to women whose cancer has spread to the lymph nodes, he said, ''There's a modest benefit (of radiation) for younger women with node-positive disease under age 50.'' But for women whose cancer has not spread to the lymph nodes, whose risk of a relapse of breast cancer is low, the benefits of radiation are small, improving survival odds by less than 1%, according to Collins.
For older women whose cancer has spread to the lymph nodes, making a decision about radiation is difficult, Collins said. He noted that older women already have a greater risk of heart disease, so radiation treatment may increase this risk even more, possibly outweighing any benefits of the treatment.
In an accompanying editorial, Dr. John M. Kurtz from University Hospital in Geneva, Switzerland, states that the report may actually be ``good news'' for radiation therapy, since it shows that the treatment can prevent breast cancer from returning and reduce breast cancer deaths.
As for the increased risk of heart-related deaths, Kurtz notes that newer radiation techniques that spare the heart and arteries as much as possible have not been shown to damage the heart.
But in the interview, Collins said that most of the increased heart risk does not appear until 20 years or so after treatment, and the effects of heart-sparing radiation have not yet been followed for that long. _____
SOURCE: The Lancet 2000;355:1739-1740, 1757-1770.


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