Implantable cardioverter-defibrillators and subsequent cancer risk: a nationwide population-based cohort study

Despite increasing use of implantable cardioverter-defibrillators (ICDs) and reports linking selected bio-implants with cancer, the cancer risk associated with implanted ICDs remains unknown. The objective of our study was to examine cancer risk among ICD recipients.

We conducted a population-based cohort study using medical registries covering the entire Danish population. We identified all first-time ICD recipients during the period of 2000-11 and determined their subsequent cancer incidence. Standardized incidence ratios (SIRs) were computed by comparing observed cancer incidence in the ICD cohort with expected cancer incidence based on national incidence rates according to age, sex, and year of diagnosis. A total of 6723 ICD recipients were followed for up to 12 years (median 2.8 years) and contributed a total of 23 254 person-years of follow-up. Compared with the general population, ICD recipients had a slightly elevated overall risk of cancer [SIR = 1.1 (95% confidence interval (CI): 1.0-1.2)]. This was driven by the cancer risk among patients with ischaemic heart disease (IHD) [SIR = 1.1 (95% CI: 1.0-1.3)], which, as expected, was particularly elevated for tobacco-related cancers [SIR = 1.4 (95% CI: 1.2-1.6)]. Importantly, ICD recipients without IHD were not at increased cancer risk [SIR = 1.0 (95% CI: 0.8-1.3)].

This nationwide population-based cohort study with up to 12-year follow-up did not indicate a causal relation between ICD implantation and cancer. However, more follow-up data are needed to entirely rule out risks for individual cancer types.