The incidence of ovarian cancer is tenfold lower than that of breast cancer. The goal of the recently published meta-analysis by Beral and colleagues, using ‘individual participant datasets from 52 epidemiological studies’, was to provide an updated assessment of the effect of menopausal hormone therapy (MHT) on ovarian cancer risk. The relative risk generated from the cited prospective studies was significantly increased but the relative risk from the retrospective studies was not. This is quite unusual since retrospective studies usually display higher levels of relative risk. No further increase was observed with increasing duration. Moreover, a number of the studies could not be adjusted for important ovarian cancer risk factors.

From the meta-analysis, it can be calculated that the absolute excess risk of 5 years of MHT for a 50-year-old UK woman is 1 in 10 000 per year, indicating a very low risk.

We conclude that this meta-analysis mostly reflects the previously published data from the Million Women Study, from which the majority of this new publication is derived.