Risks and causes of ovarian cancer
There are some factors that can increase your risk of developing ovarian cancer. A risk factor is anything that can increase your risk of cancer. A protective factor is anything that lowers the risk of cancer.
Having one or more risk factors doesn’t mean that you will definitely get ovarian cancer.
Getting older
As with most cancers, ovarian cancer becomes more common as you get older. The risk of ovarian cancer increases steeply from around 45 years. And is greatest in those aged between 75 and 79 years.
Inherited faulty genes
Between 5 and 15 out of 100 ovarian cancers (5 to 15%) are caused by an inherited faulty gene. Inherited genes that increase the risk of ovarian cancer include faulty versions of BRCA1 and BRCA2. Faults in these genes also increase the risk of breast cancer.
Having relatives with ovarian cancer does not necessarily mean that you have a faulty inherited gene in the family. The cancers could have happened by chance. But women with a mother or sister diagnosed with ovarian cancer have around 3 times the risk of ovarian cancer. This is compared to women without a family history.
If you are worried about your family history of ovarian cancer, speak to your GP. They can tell you whether you might benefit from a referral to a genetics service.
Previous cancer
You have an increased risk of ovarian cancer if you've had breast cancer in the past. The risk is higher in women diagnosed with breast cancer at a younger age. And those with oestrogen receptor negative (ER negative) breast cancer.
The increase in risk of ovarian cancer after previous cancer is likely to be partly due to inherited faulty genes such as:
- BRCA 1
- BRCA 2
- Lynch syndrome
Using hormone replacement therapy (HRT)
Using HRT after the menopause increases the risk of ovarian cancer. In the UK, 4 in 100 (4%) ovarian cancers are linked to hormone replacement therapy (HRT) use.
Remember that the increase in risk is small. HRT is helpful for many women with menopausal symptoms. Talk to your GP about the risks and benefits of taking HRT.
Smoking
Smoking can increase the risk of certain types of ovarian cancer such as mucinous ovarian cancer. The longer you have smoked, the greater the risk.
Asbestos
Asbestos is an insulating material that’s heat and fire resistant. The use of asbestos was banned in the late 1990s in the UK. It was widely used in:
- building industry
- shipbuilding
- manufacturing of household appliances
- motor industry
- power stations
- telephone exchanges
There are 3 main types of asbestos – blue, brown and white.
Asbestos is made up of tiny fibres. You can breathe these fibres in when you come into contact with asbestos.
The International Agency for Research on Cancer (IARC) classify asbestos as a cause of ovarian cancer.
Medical conditions
Studies have shown that women with endometriosis or diabetes have an increased risk of ovarian cancer. In diabetics, the increase in risk might be higher in those that use insulin.
Being overweight or obese
Having excess body fat is linked to an increase in risk of ovarian cancer.
Possible protective factors
The following factors may reduce your risk of ovarian cancer:
Taking the combined contraceptive pill
Taking the combined contraceptive pill at some point in your life reduces your risk of cancer of the ovary. Research has shown that the longer you take the pill, the more your risk is thought to be reduced. The reduction in risk lasts for tens of years after you stop taking the pill.
Having children and breastfeeding
Having children seems to reduce the risk of ovarian cancer. The more children you have, the lower the risk. Breastfeeding also reduces the risk of ovarian cancer.
This reduction in risk may be because while you are pregnant or breastfeeding you're not ovulating (releasing eggs). The fewer times you ovulate in your lifetime, the lower the risk of ovarian cancer.
Having a hysterectomy or having your tubes tied
Having your tubes tied because you don't want any more pregnancies is called sterilisation. Studies have found that having your tubes tied reduces the risk of ovarian cancer.
Until recently, most research has shown that having your womb removed (hysterectomy) may also reduce your risk of ovarian cancer. But this has become less clear in recent years. It might depend on several factors including your age when you had the operation. Any reduction in risk may be greater for younger women. Researchers continue to study this area.
Other possible causes
Stories about potential causes are often in the media and it isn’t always clear which ideas are supported by evidence. There might be things you have heard of that we haven’t included here. This is because either there is no evidence about them or it is less clear.
