The exact causes aren't well known, but scientists are growing more aware of the conditions that make ovarian cancer more likely.

First of all, as with many other cancers you are more at risk as you grow older; to be exact, after the menopause (half of all ovarian cancers are in women past the change of life.) And, also as with many other cancers, there is a genetic component, so if someone in your family has had the disease you may be slightly more prone to it yourself.

You are also more likely to develop the disease if you don't have children, use certain fertility drugs or have certain kinds of treatment such as hormone replacement therapy. Very overweight women are also at risk, while on the other hand there is some evidence that a healthy low-fat diet may lower the risk.

If you have already had breast cancer you are statistically more likely to get ovarian cancer as well. However, none of these things mean that you will get ill, just that certain conditions increase the possibility.