Study Suggests Thyroid Cancer Increases Risk of Coronary Heart Disease

Study Suggests Thyroid Cancer Increases Risk of Coronary Heart Disease

have thyroid cancer is associated with an increased risk of coronary heart disease and persists in those younger than 65 years for at least 5 years

Thyroid cancer (TC) patients are at increased risk of developing coronary heart disease, and in those younger than 65 years, this elevated risk persists for at least five years after their cancer diagnosis according to an observational study by Taiwanese researchers.

In 2020, the estimated global rate of thyroid cancer was 10.1 per 100,000 women and 3.1 per 100,000 men, although mortality rates were lower, 0.5 per 100,000 and 0.3 per 100,000 for women and men, respectively. Surgery is the mainstay of treatment in almost all cases of thyroid cancer. although radiotherapy can also be used. If the thyroid is removed, patients will require lifelong levothyroxine therapy to both replace the hormone and reduce the risk of cancer recurrence. However, in the long term the use of levothyroxine may cause marked impairment of cardiac functional reserve and physical exercise capacity. Whether these changes increase the subsequent risk of cardiovascular disease is not yet known for sure. some evidence that these patients have a higher incidence of cardiovascular disease morbidity. However, in contrast, other work has shown that the incidence of cerebrovascular disease, cerebral infarction, ischemic heart disease, ischemic myocardial infarction and heart failure is not different between those who suffer from CT and the general population.

With some uncertainty about the relationship between TC and cardiovascular disease risk, in the current study, Taiwanese researchers drew on data from a national population cohort to retrospectively examine this relationship. They chose a reference date for their analysis as the time when CT patients underwent thyroidectomy, but excluded those younger than 20 and >85 years and anyone with a history of coronary heart disease (CHD) or atrial fibrillation. They set the primary endpoint of interest as hospitalization for coronary heart disease defined in terms of fatal and nonfatal coronary heart disease. Secondary outcomes included ischemic stroke (IS) requiring hospitalization and atrial fibrillation, again requiring hospitalization. The researchers calculated a standardized incidence rate (SIR) as the proportion of observed and expected CHD cases, stratified by age and sex, within the general population.

Thyroid cancer and risk of coronary heart disease

A total of 4,274 people with thyroid cancer without coronary heart disease and a mean age of 49 years (24.4% men) were included in the analysis and followed for a mean of 3.5 years.

During follow-up, there were 69 CHD events in HT patients and the SIR was significantly higher than expected in the age-standardized population (SIR = 1.57, 95% CI 1.2 to 1.93) . However, the SI rate was not significantly different (SIR = 0.74, 95% CI 0.47 – 1), nor was the incidence of cardiovascular disease (SIR = 0.88, 95% CI 0.70 – 1 .05) or atrial fibrillation (SIR = 0.74, 95% CI 0.42 – 1.06).

When the researchers looked at SIR over time, particularly among those younger than 65 years, the elevated risk remained significant 5 years after the date of their CT diagnosis (SIR = 2.08, 95% CI: 1.5 to 2.66), although it was not significant among those older than 65 years (SIR = 1.0, 95% CI 0.57 – 1.42).

The authors concluded that patients with thyroid cancer had a higher risk of CHD than the general population without cancer and that this risk persisted for at least 5 years. They called for future research to further investigate this observed association.

Tsai MC et al. Association between thyroid cancer and cardiovascular disease risk: a nationwide observational study.. Scientific Representative 2022

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