Abstract
IntroductionTo 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.Materials and methodsAll 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.ResultsThe 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.ConclusionCompared 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.
Highlights
To minimize recurrence risk in differentiated thyroid cancer (DTC), TSH is usually lifelong suppressed with levothyroxine
Hospitalization was increased among DTC patients for atrial fibrillation (AF) (SIR 1.66, confidence intervals (CI) 95% 1.41–1.94), and women faced increased hospitalization for cerebrovascular disease (SIR 1.20 CI 95% 1.04–1.38)
Compared to the general population, DTC patients have a higher incidence in AF, and female face a slightly higher incidence in cerebrovascular disease
Summary
To minimize recurrence risk in differentiated thyroid cancer (DTC), TSH is usually lifelong suppressed with levothyroxine. Since thyrotropin (TSH) stimulates cancer cells [1, 3], patients usually receive levothyroxine in doses to suppress TSH, and it is known that a more aggressive suppression therapy reduces recurrence risk [4]. Recent guidelines recommend individualized long-term levels of TSH suppression, considering the aggressiveness of the cancer disease, and side effects of the treatment [5]. A known adverse effect of TSH suppression is subclinical hyperthyroidism, which is well studied in patients without DTC, being an established risk factor of atrial fibrillation (AF) and heart failure (HF) [6, 7]. An inflammatory process of the carotid wall has been suggested to play a role in the pathophysiological process [15]
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