During the past two decades, considerable debate has centred around whether the use of fertility drugs increases a woman’s risk of developing ovarian cancer. Most ovarian cancers are assumed to arise from the layer of epithelial cells surrounding the ovary, and it has been suggested that the repeated cycle of damage and repair that occurs with ovulation may lead to DNA damage and potentially cancer—the so called “incessant ovulation” hypothesis.1 By stimulating hyperovulation, fertility drugs might therefore increase the risk of cancer. A second hypothesis posits that increasing exposure to gonadotrophins increases the risk of ovarian cancer,2 and because gonadotrophins are used to treat infertility, such treatment might, theoretically, put patients at risk. In the linked study (doi:10.1136/bmj.b249), Jensen and colleagues use data from a large cohort study of infertile women to assess the effects of fertility drugs on the risk of ovarian cancer.3

Anxiety was initially fuelled by two studies suggesting that women who had taken …