Women taking combined hormone replacement therapy (HRT) are 2.7 times more likely to develop breast cancer than non-users, and the risk may increase with longer use, a study published in the British Journal of Cancer has found.
The researchers, from the Institute of Cancer Research in London, said that previous studies may have substantially underestimated the risk of breast cancer from combined HRT, as they did not update information about a woman’s HRT use or analyse accurately to allow for her age at menopause.
The new research was part of the Breast Cancer Now Generations Study, which is following more than 100 000 women for 40 years to investigate the causes of breast cancer.