A meta-analysis of 17 prospective studies, published in the Lancet looking at over 12,000 women diagnosed with ovarian cancer, about half of the women with ovarian cancer had received hormone therapy, and the median duration of use was 6 years. Women with current hormone therapy use had roughly a 40% increased risk for developing ovarian cancer, even among those who used hormone therapy for less than 5 years. The risk decreased with time, but 10 years after stopping, there was still an increased risk for certain type of tumors.