Women who were given hormone treatment for in-vitro fertilisation (IVF) ran twice the risk of ovarian malignancies compared with counterparts who did not undergo IVF, a study said.
Doctors in the Netherlands compared the long-term health of more than 19,000 women who had received at least one IVF ovarian stimulation treatment with just over 6,000 similarly infertile counterparts who had not been treated for IVF.
Of the 25,000 women they studied, 77 developed ovarian malignancies in the ensuing 15 years, a risk that in absolute terms was very low.
But in relative terms, the numbers were much higher in the IVF group, which had 61 out of the 77 cases compared to 16 in the non-IVF group.
Thirty of the 61 were cases of invasive ovarian cancer, which usually requires extensive surgery and chemotherapy and has a low survival rate.
The other 31 cases were borderline ovarian tumours, which have low malignancy potential and are rarely fatal but require major surgery.
After taking into account the age and how many children if any the women had had, as well as other factors that could skew the results, the researchers found a two-fold increase in the risk of ovarian malignancies in the IVF group.
But the risk did not increase with more IVF cycles, a surprise finding that will be probed further.
The study, appearing in the European journal Human Reproduction, is based on data from national health registries and women diagnosed with sub fertility problems at the Netherlands' 12 IVF clinics between 1980 and 1995.
(Sapa, October 2011)