Exposure to low-dose ionizing radiation from cardiac procedures and risk of cancer in adults with congenital heart disease

Abstract

The increasing exposure to low-dose ionizing radiation (LDIR) from cardiac imaging in adults with congenital heart disease (ACHD) has raised concerns about the risk of malignancy. To estimate the association between LDIR exposure from cardiac procedures and incident cancer in ACHD. This retrospective study of 24,833 ACHD aged 18–64 years from 1995–2009 was based on the Quebec CHD Database. Cumulative numbers and cumulative effective dose of LDIR-related cardiac procedures were measured for each patient. We assessed if high LDIR-exposure (≥ 6 procedures) was associated with an increased risk of cancer than low LDIR-exposure (≤ 1). Propensity score and inverse probability weighting were used to adjust for potential confounders. Further, we conducted a nested case-control study to investigate if LDIR-exposure was predictive of cancer using a multivariable logistic regression model. Each case was matched on sex, CHD severity, age and calendar time with 4 randomly selected controls. In over 250,791 person–years of follow-up, 602 cancer cases were observed. High LDIR-exposure was associated with a 2.6-fold increase risk of cancer (HR = 2.61, 95% CI: 2.30–2.96). In the nested case-control study, 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 (OR = 1.10 per 10 milliSieverts; 95% CI: 1.05–1.15) with an apparent dose–response relationship. The effect measure was in the same direction after excluding smoking-related cancer cases (OR = 1.10 per procedure; 95% CI: 1.05–1.16) and after applying a three-year lag time (OR = 1.09 per procedure; 95% CI: 1.03–1.14). To our knowledge, this is the first population-based study to document the association between LDIR from cardiac procedures and cancer in ACHD. This finding supports policy recommendations for radiation surveillance in CHD patients where no regulation currently exists.