Cardiovascular risks decline, but vigilence is warranted
In the pursuit of malignant tumor cells, normal tissues and organs get caught in the crossfire of cancer treatment. This has been especially true of the heart.
In earlier decades, radiation to the chest could carry deadly cardiovascular risks. Newer treatment methods, however, are putting the odds in patients' favor. We talked with Lori Pierce, M.D., University of Michigan professor of radiation oncology, about the latest developments.
Q. Who is at risk for radiation associated heart disease?
A. Technically, anyone who's getting radiation to the chest where the heart could be affected. The most likely person who could potentially be at risk is someone who has cancer in the left breast, depending on whether lymph nodes or internal mammary nodes need to be treated.
Q. What types of heart problems might patients experience after treatment?
A. Arrhythmias, or erratic heartbeats, and scarring that affects the heart's ability to pump blood can occur. Pericarditis -- or inflammation of the lining around the heart -- is sometimes seen in patients who've been treated for Hodgkin's disease. Probably the area we're most concerned about is coronary artery disease, which has been found in patients who were treated with older techniques used up through the 1980s.
Q. Have newer treatment methods reduced the risk for cardiac side effects?
A. Current radiation techniques have dramatically reduced the risk of heart-related toxicity, but we are always very mindful about the risk, particularly in left-sided breast cancer. Multiple recent studies show that there aren't big differences in incidence of cardiovascular disease among patients who were treated for left-sided breast cancer vs. those who were treated for right-sided breast cancer. It strongly suggests that the techniques we're using are dramatically less toxic to the heart than older methods.
Q. How do new techniques minimize risk?
A. Computerized three-dimensional planning allows us to see exactly where the heart is sitting and set up radiation fields so we can minimize the amount of radiation delivered to the heart. In this day and age, many of our patients are receiving other treatments, such as Adriamycin, that can damage the heart. The goal is to minimize cardiac exposure to radiation to prevent further injury. We are continuing to study the best ways to do that.
Q. How are you studying this?
A. I'm working on a study that is looking at two methods of radiation delivery to determine whether we can further reduce radiation exposure to the heart. The study, which involves people with left-sided breast cancer, will record baseline heart and lung tests before treatment and then compare them with follow-up tests a year after treatment. However, even if patients show that their heart has been exposed to radiation, it does not necessarily mean symptoms will develop down the road. Usually, it takes about 10 years for cardiac symptoms to appear.
Q. Can people who may be at risk for cardiovascular side effects do anything to lower their risk?
A. Talk to your primary care physician about your cardiac health. Find out from your oncologist whether any of your treatments carry increased risk for cardiovascular problems and share this information with your regular doctor. If you have hypertension, make sure to treat it. Discuss risks that may be associated with a family history of heart disease. Exercise, eat a heart-healthy diet and think in terms of overall health maintenance.