Post-menopausal women with elevated levels of oestrogen and testosterone have a higher risk of developing breast cancer.
The study, published in Breast Cancer Research, ranked over 800 women 
according to their hormone levels and their individual breast cancer risk. Women who had higher oestrogen or androgen levels had approximately double the usual post-menopausal breast cancer risk with each of the various sex and growth hormones increasing the risk of breast cancer by 16% when their levels were elevated.
Oestrogen was found to have the biggest effect on the risk of breast cancer as these hormones stimulate the growth of cancer cells. Future research should consider the impact of preventing rising levels of sex hormones to prevent this increase of risk.
