The impact of parity, infertility and treatment with fertility drugs on the risk of ovarian cancer. A survey.

The etiology of ovarian cancer is multifactorial. With our present knowledge, etiological factors are only found in a minority of cases. In the industrialized world, 10 new cases of ovarian cancer are developed per 100,000 women per year (1). Women who experience one or more deliveries have a reduced risk of ovarian cancer compared with nulliparous women (2-7). There is a dose-response relationship so that the risk of ovarian cancer is diminished every time a woman gives birth. It is not finally established whether the increased risk of ovarian cancer among infertile women is due to the relative high proportion of nulliparous women among these women, or whether it is due to some kind of ovarian pathology, which may be responsible for the infertility as well as for the increased risk of ovarian cancer. One of the difficulties in assessing the significance of infertility for ovarian cancer is the close connection between parity and fertility and between nulliparity and infertility (8). Furthermore, an epidemiological analysis of these problems has to face the fact that these ‘spontaneous conditions’ are influenced by, for example, the treatment with