April 17th, 2013
Cardio Oncology: Counseling Women on The Cardiovascular Risks of Radiation Therapy
This post is the second in a series inspired largely by the recent publication of the study Risk of Ischemic Heart Disease in Women after Radiotherapy for Breast Cancer in the New England Journal of Medicine. Our participants included invited study authors Candace Correa and Kazem Rahimi; author of an accompanying editorial, Javid J. Moslehi; and Jerry Walker, who has appointments in both the Division of Cardiology and the Department of Radiology at the University of Utah School of Medicine, to discuss this important topic. John Ryan moderated. See the previous post here.
Dr. Ryan: When radiation-therapy is being initiated do you feel that women should be counseled about the cardiovascular risks and what would you tell them?
Dr. Rahimi: Yes, I think that such counseling should be the standard of care (and I believe this is already the case in most oncology departments). Prior to our study it was difficult to have an informed discussion about absolute risks (and benefits) of radiotherapy with patients. Now, doctors can clearly say: without radiotherapy you have a x% chance of suffering a major cardiac event over the next y years. Undergoing radiotherapy would expose your heart to irradiation by z%. This is expected to increase your risk of suffering a major cardiac event from a% to b%. The conversation would then continue by explaining the expected benefits of radiotherapy for prevention of cancer-related events.
Dr. Walker: I think we live in an age in which patients expect to be told what the risks and benefits are for any given treatment. Certainly, a patient who is treated for cancer wants the treatment that will result in the best chance of cure. They will need to know that there might be side effects to the treatments offered. I think we as physicians can help them balance these risks and actually help them plan for the possible outcome of a coronary event. I believe that this gives patients an important sense of control over their situation.
Dr. Correa: The most important thing to remember is that radiotherapy significantly reduces the risk of breast cancer recurrence and increases breast cancer specific survival for many patients. However, women should be counseled about the potential cardiovascular risks of radiotherapy. I tell my patients that there was an elevated risk of developing heart disease after breast cancer radiotherapy using older techniques, and there may be a smaller elevated risk with modern radiotherapy. One of the key findings of the NEJM paper is that the risk of developing heart disease is a function of the dose of radiation that the heart receives. With modern radiotherapy we can employ specialized techniques to reduce incidental irradiation of the heart and thereby reduce this risk. Before the NEJM study we did not have a good idea of what dose limits to use for incidental cardiac irradiation and now we have at least a rough idea of safer cardiac doses.
Dr. Moslehi: The Darby paper suggests that women with risk factors for ischemic cardiac disease or women with a history of ischemic cardiac disease are especially susceptible to an ischemic cardiac event. Therefore, these women should be under the care of a cardiologist at the time of initiation of breast cancer therapy and radiation.