Cardiovascular Incidence in 6900 Patients with Differentiated Thyroid Cancer: a Swedish Nationwide Study

To minimize recurrence risk in differentiated thyroid cancer (DTC), TSH is usually lifelong suppressed with levothyroxine. A common consequence of this treatment is subclinical hyperthyroidism which can induce cardiovascular disease (CV). This study's aim was to compare CV incidence in DTC patients with the general population in Sweden.

All Swedish patients diagnosed with DTC in 1987-2013 were included in the cohort study. Lifelong TSH suppression treatment was assumed to be administered to patients in compliance with prevalent national guidelines. Patients were followed from 1 year after DTC diagnosis until December 31, 2014, death, or migration. The event of interest was hospitalization due to any of the following diseases: atrial fibrillation (AF), cerebrovascular disease, cerebral infarction, ischemic heart disease, ischemic heart attack, and heart failure. Standardized incidence ratios (SIRs) were calculated to compare CV incidence between DTC patients and the general population.

The cohort consisted of 6900 patients with DTC. Hospitalization was increased among DTC patients for AF (SIR 1.66, CI 95% 1.41-1.94), and women faced increased hospitalization for cerebrovascular disease (SIR 1.20 CI 95% 1.04-1.38). Regarding the remaining CV diseases, no consistent difference in SIR between the groups was observed.

Compared to the general population, DTC patients have a higher incidence in AF, and female face a slightly higher incidence in cerebrovascular disease. However, there was no difference in hospitalization for other studied CV diseases between DTC patients and the general population.