Low levels of thyroid hormone may reduce the risk of breast cancer: evidence from a meta-analysis

Abstract

Background: At present, the relationship between hypothyroidism and the risk of breast cancer is still inconclusive. This meta-analysis was used to systematically assess the relationship between hypothyroidism and breast cancer risk, and to assess whether thyroid hormone replacement therapy can increase breast cancer risk.Methods: The relevant articles about hypothyroidism and the risk of breast cancer were obtained on the electronic database platform. Relevant data were extracted, and odd ratios with corresponding 95% confidence intervals(95% CI) were merged using Stata SE 12.0 software. A total of 19 related studies were included in the meta-analysis, including 6 cohort studies and 13 case-control studies.Result: The results show that hypothyroidism can reduce the risk of breast cancer(odd ratios= 0.90, 95% CI 0.77-1.03), but in Asian populations, patients with hypothyroidism have an increased risk of breast cancer(odd ratios=1.17, 95% CI 0.98-1.35). In addition, patients who received thyroid hormone replacement therapy had a lower risk of developing breast cancer(odd ratios=0.87, 95% CI 0.65-1.09).Conclusion: Hypothyroidism and thyroid hormone replacement therapy reduces the risk of breast cancer, suggesting that low levels of thyroid hormone may be beneficial to breast cancer prevention. Due to the limited number of studies included more large-scale, high-quality, long-term prospective cohort studies are needed.