Doctors cannot always explain why one woman develops ovarian cancer and another does not. However, we do know that women with certain risk factors may be more likely than others to develop ovarian cancer. A risk factor is something that may increase the chance of developing a disease.
Studies have found the following risk factors for ovarian cancer:

• Family history of cancer: Women who have a mother, daughter, or sister with ovarian cancer have an increased risk of the disease. Also, women with a family history of cancer of the breast, uterus, colon, or rectum may also have an increased risk of ovarian cancer.
  
  If several women in a family have ovarian or breast cancer, especially at a young age, this is considered a strong family history. If you have a strong family history of ovarian or breast cancer, you may wish to talk to a genetic counselor. The counselor may suggest genetic testing for you and the women in your family. Genetic tests can sometimes show the presence of specific gene changes that increase the risk of ovarian cancer.

• Personal history of cancer: Women who have had cancer of the breast, uterus, colon, or rectum have a higher risk of ovarian cancer.

• Age over 55: Most women are over age 55 when diagnosed with ovarian cancer.

• Never pregnant: Older women who have never been pregnant have an increased risk of ovarian cancer.

• Menopausal hormone therapy: Some studies have suggested that women who take estrogen by itself (estrogen without progesterone) for 10 or more years may have an increased risk of ovarian cancer.

Scientists have also studied whether taking certain fertility drugs, using talcum powder, or being obese are risk factors. It is not clear whether these are risk factors, but if they are, they are not strong risk factors.
Having a risk factor does not mean that a woman will get ovarian cancer. Most women who have risk factors do not get ovarian cancer. On the other hand, women who do get the disease often have no known risk factors, except for growing older. Women who think they may be at risk of ovarian cancer should talk with their doctor.