NEW ORLEANS – The greater the lifetime number of cardiac procedures entailing exposure to low-dose ionizing radiation, the higher the associated cancer risk in adults with congenital heart disease, Sarah Cohen, MD, reported at the American Heart Association scientific sessions.
This finding takes on added clinical import because the use of such procedures has increased markedly in patients with adult congenital heart disease, added Dr. Cohen of McGill University in Montreal.
She presented analyses of nearly 25,000 patients in the Quebec congenital heart disease database who were ages 18-64 with no history of cancer in January 1995; 602 of them were diagnosed with cancer during follow-up through 2009. Each was matched to four cancer-free controls in the database on the basis of age, sex, congenital heart disease severity, and calendar year.
Patients with a lifetime total of four or five cardiac procedures involving exposure to low-dose ionizing radiation were 1.7-fold more likely to be diagnosed with cancer during follow-up than were those with a history of no such procedures or just one. With a lifetime history of six or more of the procedures, the relative risk climbed to 2.2-fold.
Nearly 90% of the malignancies were genitourinary, respiratory, digestive, breast, or hematologic cancers.
Dr. Cohen and her coinvestigators also conducted a cohort study comparing the relative risk of developing cancer in 1,781 high-exposure Quebec adults in the database who had a lifetime history of four or more cardiac procedures involving radiation exposure to more than 20,000 others with a history of not more than one such procedure. The high-exposure group had a 3.3-fold greater rate of malignancy during follow-up.
In a separate study, Dr. Cohen’s McGill colleagues analyzed the Quebec database and documented the sharp rise over time in low-dose ionizing radiation cardiac procedures, including catheter-based diagnostic procedures, structural heart interventions, nuclear procedures, coronary interventions, computed tomography scans of the chest, coronary interventions, and insertion or repair of pacemakers and implantable cardioverter-defibrillators. In 1990, the rate was 18.5 such procedures per 1,000 patients per year. By 2005, it had nearly tripled to 51.9 per 1,000 per year. The age at first procedure dropped from 5 years to 9 months (Circulation 2016 Jan 5;133[1]:12-20).
Dr. Cohen reported having no financial disclosures.