Ovarian cancer: causes and risk factors
About 1 in every 50 (2% of) women in the UK develops ovarian cancer during her lifetime.
The causes of ovarian cancer are not yet completely understood. The risk of developing ovarian cancer is very low in young women and increases as women get older. More than 8 out of 10 (80% of) ovarian cancers occur in women over the age of 50. On this page we’ve listed some factors that are known to affect a woman’s chance of developing ovarian cancer. Some increase the risk and some decrease it.
Hormonal factors that increase the risk of developing ovarian cancer
Hormonal factors that decrease the risk of developing ovarian cancer
Starting periods at a young age
Taking the contraceptive pil
Having a later menopause
Having children (the risk decreases with each additional pregnancy
Taking hormone replacement therapy (HRT) (the risk decreases after stopping taking it)
Women who are taller than 1.7m (5ft 7in) are slightly more likely to get ovarian cancer than shorter women.
Endometriosis is a condition where the lining of the womb grows outside the womb. Having endometriosis slightly increases the risk of developing ovarian cancer.
Having ovarian cysts before the age of 30 increases your risk of developing ovarian cancer in future. But most women who have had ovarian cysts before the age of 30 won’t ever develop ovarian cancer.
Smoking cigarettes increases the risk of developing a type of ovarian cancer called mucinous cancer.
Some studies have found a link between being very overweight (obese) and an increased risk of developing ovarian cancer.
Eating a diet high in animal fats and low in fresh fruit and vegetables may increase the risk of developing ovarian cancer.
If your mother or sister has had ovarian cancer, this slightly increases your risk of developing it. But the risk is still low – about 1 in 20 (5%).
We have more information available if you are worried about ovarian cancer and genetics.
Women who have two or more close relatives who’ve had ovarian cancer or certain other types of cancer may be at a higher risk.
A small number of ovarian cancers, about 1 in 10 (10%), are thought to be due to an inherited altered gene (genetic mutation).
If a family has an altered gene, usually several relatives on the same side of the family are diagnosed with ovarian cancer or related cancers, such as breast, bowel or womb cancer. People in the family may also be diagnosed with cancers at a particularly young age.
Doctors are most interested in the history of cancer in your close relatives (first-degree relatives and second-degree relatives).
First-degree relatives are your parents, brothers, sisters and children.
Second-degree relatives are your grandparents, grandchildren, aunts, uncles, nieces and nephews.
If any of the following are present on one side of your family (either your father’s or your mother’s side), it’s possible that there may be an inherited faulty gene that increases your risk of developing ovarian cancer:
Ovarian cancer in at least two close relatives, where at least one is a first-degree relative.
Ovarian cancer in a first-degree relative and a first- or second-degree relative diagnosed with breast cancer under the age of 50 (or both cancers in the same person).
Ovarian cancer in a first-degree relative and two relatives (who are first-degree relatives of each other) diagnosed with breast cancer before they reached an average age of 60.
Ovarian cancer in one close relative and colon (bowel) and/or womb (endometrial) cancers in three relatives.
We have more information available about cancer genetics.
Online risk assessment
If you’re worried about the occurrence of ovarian cancer in your family and whether there might be an inherited genetic link, we have an online tool you can use to assess your risk of developing breast or ovarian cancer. OPERA (Online Personal Education and Risk Assessment) is an online interactive programme that will offer you personalised information and support about your inherited cancer risk.
If you think you may have an increased risk of developing ovarian cancer, you should contact your GP, who can refer you to a genetic counselling clinic. These clinics are based in hospitals, and you will be seen by a genetics specialist who can check your family history to see whether you are likely to be at increased risk.