Women who have an increased levels of thyroid hormones are more susceptible to breast cancer, revealed a new study.
Thyroid hormones are of two types namely Triiodothyronine (T3) and Thyroxine (T4) that play a vital role in body metabolism, heart rate and protein synthesis. These two hormones should be at moderate levels and if they are high, the condition is termed as hyperthyroidism, and if low, it is termed as hypothyroidism.
‘Thyroid hormones have a similar effect as estrogen which triggers the development of breast cancer in women with hyperthyroidism than hypothyroidism.
A new study published in the European Journal of Endocrinology
reported that women who have an elevated level of thyroid hormones have an increased risk of breast cancer while those with lesser level of thyroid hormones have a reduced risk of breast cancer.
Danish researchers examined nationwide registries to identify women with low and high levels of thyroids between 1978 and 2013. The data included four million women, of which 61,873 women were diagnosed with hypothyroidism and 80,343 women were diagnosed with hyperthyroidism.
They found that hyperthyroid women were 11 percent more likely to develop breast cancer, whereas those with hypothyroidism were 6 percent less likely to develop the condition.
"Our findings emphasize the importance of raising awareness of breast cancer in women with hyperthyroidism, and further our understanding of this potential risk," said lead author Dr. Mette Sogaard from Aarhus University Hospital in Denmark.
"In vitro experiments show that sex hormones such as estrogen play an important role in the proliferation of breast-cancer cells. High levels of thyroid hormone levels can have estrogen-like effects, which may explain why hyperthyroidism is associated with higher risk of breast cancer," added Sogaard.