Researchers at McGill University Health Centre (MUHC) and Jewish General Hospital in Quebec have found that even low doses of radiation from cardiac imaging or other procedures performed after a heart attack, such as CT scans, angiography and nuclear scans can cause cancer.
The increase in the risk of cancer after such diagnostic tests is a concern since there has been an increased use of these types of diagnostic tests in recent years. In many medical centers, they are replacing diagnostic tests that don’t use radiation. The medical profession admit they know little about the effects of such tests or whether radiation causes cancer.
The records of 82,861 patients with heart attacks but no history of cancer were studied at MUHC. Of this number, 77% underwent at least one procedure involving low-dose radiation within a year of having the heart attack.
"We found a relation between the cumulative exposure to low-dose ionizing radiation from cardiac imaging and therapeutic procedures after acute myocardial infarction, and the risk of incident cancer," Dr. Louise Pilote, researcher in epidemiology at the Research Institute of the MUHC and director of the Division of Internal Medicine at the MUHC, wrote with co-authors. "Although most patients were exposed to low or moderate levels of radiation, a substantial group were exposed to high levels and in general tended to be younger male patients with fewer comorbidities."
Most of the heart attack sufferers were men, while 31.7% were women, with an average age of 63.2 years.
There were 12,020 cases of cancer found during follow-ups on these patients, with two-thirds of the cancer cases affecting the abdomen/pelvis and chest areas.
"These results call into question whether our current enthusiasm for imaging and therapeutic procedures after acute myocardial infarction should be tempered," Pilote and the other co-authors concluded. "We should at least consider putting into place a system of prospectively documenting the imaging tests and procedures that each patient undergoes and estimating his or her cumulative exposure to low-dose ionizing radiation."