Many post-menopausal women, who have not had a hysterectomy, use
combined HRT (containing progestagen and oestrogen) or tibolone
(synthetic HRT), because oestrogen-only preparations are known
to increase the risk of womb cancer. But little information
exists on the incidence of womb cancer in users of these other
therapies. Valerie Beral (Cancer Research UK and University of
Oxford) and colleagues recruited 717, 000 postmenopausal women
from the UK, aged 50-64 years, who had no previous history of
cancer and had not had a hysterectomy, into the Million Women
Study, between 1996 and 2001. The women filled in questionnaires
about their use of HRT and other personal details and were
followed up for an average of 3.4 years. Just under half of the
women reported that they had used some form of HRT.1320 womb
cancers were diagnosed at follow-up. The investigators found
that, compared with women who had never used HRT, women who last
used oestrogen-only HRT or tibolone had a higher risk of womb
cancer overall and tha