Potential causes of ovarian cancer

There are some risk factors that can increase the chances of someone developing ovarian cancer. If you have a risk factor, it does not mean you will get ovarian cancer. And if you don’t have any risk factors, it doesn’t mean you won’t get ovarian cancer. Usually, cancer is caused by a mixture of different risk factors.

Factors that can affect your risk of getting ovarian cancer include:

  • age
  • hormonal factors – for example, taking the pill and having children
  • previous or current medical conditions
  • weight
  • smoking
  • family history.

Talk to your doctor if you’re worried about any of these risk factors. They can let you know where to find more information and support.

Risk factors

About 7,000 women in the UK are diagnosed with ovarian cancer every year.

We don’t know exactly what causes it. But, we know some of the risk factors that may increase the chances of developing ovarian cancer.

Having a particular risk factor doesn’t mean you will definitely get cancer – just as not having any risk factors doesn’t mean you won’t. Usually, cancer is the result of the combination of several risk factors.


Age

Age is a common risk factor for many cancers. 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. It is rare in women under 30.


Hormonal factors

Doctors think the number of times a woman releases an egg (ovulates) may be linked to ovarian cancer risk. Women who don’t have children have a higher risk of developing ovarian cancer.

Certain factors that reduce ovulation may help lower the risk of ovarian cancer, for example, taking the contraceptive pill, having children and breastfeeding.

Hormone replacement therapy (HRT)

HRT increases the risk of developing ovarian cancer but only slightly. About 1% of cases may be linked with taking HRT. The risk only slightly decreases after stopping taking it.


Medical conditions

Previous breast cancer

Women who have breast cancer may have an increased risk of developing ovarian cancer. This may be because these cancers have some risk factors in common.

Endometriosis

Endometriosis is a condition where the lining of the womb grows outside the womb. Having endometriosis slightly increases the risk of developing ovarian cancer.

Diabetes

Women with diabetes may have a slightly higher risk of developing ovarian cancer.


Lifestyle factors

Weight

Some studies have found a link between being very overweight (obese) and an increased risk of developing ovarian cancer. We have more information about managing a healthy weight.

Taller women may also have a higher risk of ovarian cancer.

Smoking

Smoking cigarettes may slightly increase the risk of developing mucinous ovarian cancer.

We have more information about giving up smoking. There are some useful tips to help you quit.


Family history

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%).

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.


Inherited risk

A small number of ovarian cancers, up to about 10–15%, are thought to be due to an inherited change (alteration) in a gene. The altered genes that increase the risk of developing ovarian cancer and also breast cancer are BRCA1 and BRCA2.

If a family has an altered gene, usually several relatives on the same side of the family have had ovarian cancer or related cancers, such as breast, bowel or womb cancer. They may have also have been diagnosed at a particularly young age.

We have more information about family history and inherited risk of ovarian cancer.