A recent peer-reviewed article in the Journal of the American College of Cardiology is confirming suspected links between cancer treatment and cardiovascular risk. Leon Cannizzaro, III, MD, FACE, with Alabama Cardiovascular Group, wants physicians to be aware of the increased risk and be prepared to monitor their patients accordingly.
"We certainly know that cancer treatments are associated with cardiovascular risk," he said. "The field of cardio-oncology was born based on that realization. The better oncologists did with their treatment regimens to keep cancer patients alive, the more we realized some of the long-term side effects of chemotherapy and radiation therapy."
The new study is more specific about those risks, focusing on women under 55 years of age with breast cancer, trying to identify if the cardiovascular risk was higher based on whether the cancer and resulting radiation therapy were left sided or right sided.
"This study confirmed the suspicion that younger women who received left-sided radiation treatment were more likely to develop cardiovascular disease than women with right-sided cancer. It seems obvious, since the heart is on the left side of the chest, but this quantifies it in a way that stood out," Cannizzaro said. "The best studies are randomized, controlled studies. This was a retrospective study where they used a cardiovascular health questionnaire, so of course, there are going to be limitations on that. But it's a very well-done study."
The study presented some significant statistics. For example, women without breast cancer in the 25 to 39 year-old age group have a risk of heart disease that's less than one percent, whereas women in the same age group who had received left-sided radiation had a 5.9 percent risk. In the 40 to 54 year-old age group, women without breast cancer had a 6.6 percent risk of heart disease, compared to women of the same age who received left-sided radiation having a risk of 18.7 percent.
While this study was quite targeted, Cannizzaro said it should call attention to other cases where there is radiation therapy in the area of the heart. "It would be helpful to study the radiation effects on men with Hodgkin's lymphoma," he said. "In the 80s and 90s, they would have received relatively high doses of radiation to their chest. We are now seeing some of those long-term effects."
The article defined heart symptoms as a heart attack or chest pain related to heart disease. "The initial onset of cardiac problems was about five years, at least, following treatment," Cannizzaro said. "They followed these patients for almost 30 years. So down the road, we need to be aware of this and treat these patients as if they have a higher risk of heart disease, because they do.
"We may see patients who have a history of breast cancer, and when they come to their provider with chest pain or heart failure symptoms, it's important to ask questions to learn more about their breast cancer. What kind of treatment did they have? What kind of chemotherapy? Certain types of chemotherapy can cause heart damage. Was it left or right sided, and did they receive radiation? That can put a primary provider on alert when patients have some of these symptoms."
Cannizzaro suggests that when physicians screen patients for possible heart symptoms, they be more specific than simply asking about chest pain. "Nobody wants to say they have chest pain, but tightness and heaviness in our book is the same. So I'll ask, 'Is it sharp, stabbing, burning, aching, squeezing, tightness, pressure?' Any of those things is a type of chest pain, and from there, the patient is describing the nature of that pain."
The most recent treatment of a patient in the study was 2008, and cancer treatment has continued to evolve. "Oncologists are doing more now to protect the heart when they are doing left-side radiation," Cannizzaro said. "So some of these effects are going to be mitigated, but it is still something we need to be aware of.
"One of those mitigation techniques is the breath-hold technique. If you take a deep breath, your diaphragm goes down in your chest. Your heart sits on your diaphragm, so that holds your heart down, and they shoot the beam while you are holding that deep breath. That helps minimize how much the radiation actually affects the heart."
Cannizzaro cautions all physicians to consider these risks when treating women with a history of breast cancer. "You need to put them in a higher risk category if they report any of these chest symptoms. Keep it on your radar."