Breast cancer link to overactive thyroid

Women with an underactive thyroid gland - also known as hypothyroidism - were six percent less likely to develop breast cancer, they concluded. Picture AP/Franka Bruns

Women with an underactive thyroid gland - also known as hypothyroidism - were six percent less likely to develop breast cancer, they concluded. Picture AP/Franka Bruns

Published Feb 11, 2016

Share

London - Women with an overactive thyroid gland have an increased risk of breast cancer, a study suggests.

Those with hyperthyroidism – a condition which occurs when there is too much thyroid hormone in the body – were 11 percent more likely to develop the condition than other women, researchers found.

But women with an underactive thyroid gland - also known as hypothyroidism - were six percent less likely to develop breast cancer, they concluded.

Experts in Denmark used national registers to identify women with over and underactive thyroids between 1978 and 2013.

They then estimated their risk of breast cancer compared with the expected risk in the general population. The scientists, whose study is published in the European Journal of Endocrinology, looked at data on more than four million women and found 80 343 women with an overactive thyroid and 61 873 with an underactive thyroid.

Lead author Dr Mette Sogaard, from Aarhus University Hospital in Denamrk, said: “Experiments show that sex hormones such as oestrogen play an important role in the proliferation of breast cancer cells.

“High levels of thyroid hormone levels can have oestrogen-like effects, which may explain why hyperthyroidism is associated with higher risk of breast cancer.”

Daily Mail

Related Topics: