Menopausal women prescribed hormone therapy for more than a year have a greater risk of breast cancer compared with those who have never used the treatment, a landmark study has found.

The elevated risk persists even after ceasing HRT and for up to 15 years post-therapy, the UK researchers say.

The finding is at odds with recent health messages, with Jean Hailes for Women’s Health advising that taking menopausal HRT for 2-5 years “causes little if any increase in breast cancer risk”.

In a meta-analysis of 24 prospective epidemiological studies between 1992 and 2018, the University of Oxford-led team analysed data from more 108,000 women who developed breast cancer at a mean age of 65 years.