Not all Women Undergoing Radiotherapy for Breast Cancer have Increased Heart Disease Risk: Researchers

Although there is some risk of heart disease in women undergoing radiotherapy for breast cancer, the benefits greatly outweigh the potential risks involved, researchers from University of Oxford and Scandinavia say. A new study has now found that women who are more likely to have a higher risk of heart disease post treatment can be identified and treated with alternative therapies.

Radiotherapy not only treats cancer, but is known to lower the risk of the cancer coming back. However, during the treatment, the heart gets some radiation, especially if the left breast is being treated for cancer.

Now, for the first time, a study that included 2,000 women from Sweden and Denmark has been able to find how much radiation will raise the risk of heart disease in post-breast cancer treatment.

Researchers say that doctors will now be able to assess the individual risk factor for developing heart disease after radiotherapy for breast cancer.

"We carried out this work because doctors could not reliably estimate the risk of heart disease in women treated with radiotherapy for breast cancer. Doctors can now estimate the risk and know that in most cases it will be very small so that they can reassure their patients. In addition, the few women for whom radiotherapy poses undue risk can now be identified, so that alternative techniques can be considered," professor Sarah Darby from the Clinical Trial Service Unit (CTSU) at the University of Oxford and lead author of the study, said.

For the study, researchers looked at the medical records of 2,168 women who underwent radiotherapy for breast cancer between 1958 and 2001. In the study group, 963 later developed heart disease. Researchers then looked at the individual records of each patient and calculated the amount of radiation that they had received.

The amount of radiotherapy given during the treatment is measured in Gary (Gy), according to a news release from the University of Oxford. In cases where the woman has tumor on the right side, the heart gets some 1-2 Gy. For the tumor that's on the left side, the heart is exposed to higher levels of radiotherapy.

Not all women have equal risk of having a heart disease post treatment. However, for women who have prior history of heart disease, small distance between chest and heart or other conditions may have an increased risk of heart disease following radiotherapy. According to researchers, their study will help identify these at-risk women and design radiotherapy to suit them.

"Already our work is being used in cancer centres throughout the world and we've heard it's making a difference to patients. It's important to remember that for most women treated today the benefits of breast cancer radiotherapy far outweigh the risks," said Dr. Carolyn Taylor, another study author from Oxford University's CTSU.

The study is published in the New England Journal of Medicine.

According to estimates by the National Cancer Institute, 232,340 new cases of female breast cancer will be diagnosed in 2013 in the U.S. and nearly 40,000 women will die due to breast cancer.

Breast cancer is one of the most common cancers diagnosed in women in the U.S. Despite its high prevalence, researchers aren't sure why normal breast cells turn cancerous. According to most experts, breast cancer is caused by a combination of genetic, hormonal and environmental factors.