A small number of cases happen in women who have a family history of ovarian or breast cancer. If you have 2 or more close family members who have had these cancers then you should see your GP for possible referral to a clinical geneticist.
Being overweight seems to be a risk factor. Endometriosis and taking hormone replacement therapy (HRT) may increase the risk slightly, whereas previous pregnancies, breast feeding and taking the oral contraceptive pill reduce the risk a little.
There is no national screening programme for ovarian cancer, as no test has proved reliable enough. Ca125 (a blood test) is raised in about 80% of cases but it can be raised in other conditions, and can also be normal in early ovarian cancer, giving false reassurance. Ultrasound scanning is good at diagnosing established cancer of the ovary, but it is not reliable enough at picking up all early cancers to be used as a screening tool.