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Each year, about 6,800 women in the UK are diagnosed with ovarian cancer. The causes are not yet completely understood but some factors are believed to increase the risk.
As with many cancers, the main risk factor for ovarian cancer is age. The risk of developing ovarian cancer is very low in young women and increases as women get older. More than 8 out of 10 (85%) ovarian cancers occur in women over the age of 50. Most ovarian cancers occur in women who have had their menopause.
Some other factors are known to increase a woman’s chance of developing ovarian cancer. These include a strong family history of ovarian or breast cancer, obesity, use of hormone replacement therapy (HRT), and infertility.
There are some protective factors| that may reduce a woman's risk of ovarian cancer such as having children, using the contraceptive pill, and breastfeeding.
A risk factor is something that increases your chances of developing a health condition such as cancer. For example, smoking is the best known risk factor for lung cancer. Age is another risk factor for many cancers. Most people who develop cancer are over the age of 65. Having a particular risk factor does not mean you definitely will get cancer, just as people without any known risk factors can develop cancer.
Women who have not had children are slightly more likely to develop ovarian cancer than women who have, although the risk is still very low.
Starting your periods early or having a late menopause slightly increases your risk of ovarian cancer.
Using hormone replacement therapy (HRT) can slightly increase the risk. When HRT is stopped the risk of ovarian cancer gradually reduces to the same level as women who haven't taken HRT.
Some research has shown that infertility may slightly increase the risk of developing ovarian cancer.
Having endometriosis – a condition where the womb lining grows outside the womb – may increase your risk of ovarian cancer.
Being overweight may increase your risk of developing ovarian cancer.
Eating a diet high in animal fats and low in fresh fruit and vegetables may also increase your risk.
About 5–10 in 100 (5–10%) of ovarian cancers are caused by an inherited faulty gene| in the family. Women who have had breast cancer| have an increased risk of ovarian cancer. This is because breast and ovarian cancer can be caused by the same faulty genes. If any of the following are present in one side of your family, it’s possible that there may be an inherited faulty gene:
Having one elderly relative with ovarian cancer doesn’t necessarily increase your risk of ovarian cancer.
Your close relatives are your parents, children, brothers and sisters. These are sometimes called your first-degree relatives.
You may find it helpful to read our information on cancer genetics|, which explains how cancer sometimes runs in families, or our section specifically about ovarian cancer and 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 software program that will offer you personalised information and support about your inherited cancer risk.
If you think you may have an increased risk of getting 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.
If two or more of your close relatives have had ovarian cancer you may want to consider having testing (screening) for ovarian cancer|. Screening is still being researched to see how effective it is.
The following may reduce the risk of ovarian cancer:
Content last reviewed: 1 February 2011
Next planned review: 2013
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.
OPERA is our Online Personal Education and Risk Assessment tool, which might help if you are worried about your risk of ovarian or breast cancer.
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© Macmillan Cancer Support 2013
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