Exposure to Low-Dose Ionizing Radiation from Cardiac Procedures and Malignancy Risk in Adults with Congenital Heart Disease
Background—Adults with congenital heart disease (ACHD) are exposed to increasing amounts of low-dose ionizing radiation (LDIR) from cardiac procedures. Cancer prevalence in this population is higher compared to the general population. This study estimates the association between LDIR exposure from cardiac procedures and incident cancer in ACHD patients.
Methods—The study population derived from the Quebec CHD Database. We measured cumulative numbers of LDIR-related cardiac procedures for each patient until one year before time of cancer diagnosis or administrative censoring. To assess the association between LDIR exposure and cancer risk, we conducted a nested case-control study and matched cancer cases with controls on sex, CHD severity, birth year and age.
Results—The study included 24,833 ACHD patients aged 18-64 years from 1995-2009. In over 250,791 person-years of follow-up, 602 cancer cases were observed (median age: 55.4 years). The cumulative incidence of cancer estimated up to age 64 was 15.3% (95% CI, 14.2-16.5). Cases had more LDIR-related cardiac procedures than controls (1,410 versus 921 per 1,000 ACHD patients, p<0.0001). Cumulative LDIR exposure was independently associated with cancer (OR: 1.08 per procedure; 95% CI, 1.04-1.13). Similar results were obtained using dose estimates for LDIR exposure (OR: 1.10 per 10 milliSieverts; 95% CI, 1.05-1.15) with a possible dose related response. The effect measure was in the same direction and the association was persistent for exposure≥6 procedures in all sensitivity analyses: after excluding most smoking-related cancer cases (OR: 1.10 per procedure; 95% CI, 1.05-1.16 and OR when exposure≥6 procedures: 3.08; 95% CI, 1.77-5.37), and after applying a three-year lag period (OR: 1.09 per procedure; 95% CI, 1.03-1.14 and OR when exposure≥6 procedures: 2.58; 95% CI, 1.43-4.69).
Conclusions—To our knowledge, this is the first large population-based study to analyze and document the association between LDIR-related cardiac procedures and incident cancer in ACHD population. Confirmations of these findings by prospective studies are needed to reinforce policy recommendations for radiation surveillance in CHD patients where no regulation currently exists. Physicians ordering and performing cardiac imaging should ensure that exposure is "as low as reasonably achievable" without sacrificing quality of care.
- Received May 1, 2017.
- Revision received November 10, 2017.
- Accepted November 17, 2017.