Breast cancer is one of the most common cancers in women. Learning more about breast cancer and how to prevent and detect it early is a topic of concern for many people. In recent years, the prevalence of thyroid diseases such as hyperthyroidism and hypothyroidism has also increased dramatically in China, and people have become more aware of these two diseases. However, you will not expect that there is a relationship between thyroid disease and breast cancer, although the thyroid and breast are in two separate places. Today, I’m going to introduce you to a new discovery about the relationship between these two diseases. It is not by chance that scientists have gone to study the relationship between the two. This is because studies have shown that high levels of thyroid hormones have estrogen-like effects; and the development of many types of breast cancer is associated with hormones such as estrogen. Therefore, scientists wanted to find out if too much thyroid hormone promotes the development of breast cancer. A recent study shows that the answer may be yes. The thyroid gland is a butterfly-shaped gland at the base of the neck that is responsible for producing thyroid hormones. Thyroid hormones affect almost every cell in the body and have many very important functions, such as regulating metabolism, heart rate, and body temperature. When you have hyperthyroidism, or an overactive thyroid, the thyroid gland produces too much thyroid hormone, which can lead to weight loss, thinning hair, sweating, anxiety, and a rapid heart rate. Women are 5-10 times more likely to have an overactive thyroid than men. When hypothyroidism (i.e., hypothyroidism), or low thyroid function, the thyroid gland does not produce enough thyroid hormone, you can experience weight gain, weakness, constipation, depression, dry hair, and a slowed heart rate. As with hyperthyroidism, hypothyroidism is more likely to occur in women than in men. Study finds link between thyroid disease and breast cancer This recent study explored whether an overactive or underactive thyroid gland affects the risk of breast cancer. The study was conducted among Danish women diagnosed with thyroid disease between 1978 and 2013, of whom 60,000 subjects had hypothyroidism and more than 80,000 had overactive thyroid. The study followed the patients for 5-7 years and found that women with an overactive thyroid had an 11% increased risk of breast cancer. However, women with hypothyroidism had a 6% lower risk of breast cancer. Further research needed on whether thyroid hormones are a causative factor This study may lead to the conclusion that high thyroid hormone levels promote breast cancer. However, experts point out that this study only establishes an association between thyroid hormones and breast cancer, but does not prove a causal relationship between thyroid function and breast cancer, meaning it is not certain that an overactive thyroid gland directly causes breast cancer. There are other possibilities, such as whether women with a high risk of hyperthyroidism also have a high risk of breast cancer, or whether hyperthyroidism treatment is a trigger for an elevated risk of breast cancer. Another theory is that women with hyperthyroidism see their doctors more frequently and are therefore more likely to be screened for other diseases such as breast cancer, and therefore have a correspondingly high incidence of research. More research is needed to elucidate these issues and to study the relationship between thyroid hormones and breast cancer clearly. What is clear, however, is that regular visits to the doctor and regular breast cancer screening examinations are essential for women with overactive thyroid function.