Ovarian cancer risks and causes | Cancer Research UK
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Ovarian cancer risks and causes

This information is about risk factors for epithelial ovarian cancer, which makes up almost 9 out of 10 cases (90%) of ovarian cancer. Epithelial means surface layer. So this is cancer of the surface layer covering the ovary.

We do not know exactly what causes epithelial ovarian cancer. But there are some things that may increase the risk. And other factors that seem to reduce it.

As with most cancers, the risk of developing ovarian cancer increases with age. Most cases are in women who are past their menopause. A family history of cancer is one of the most important risk factors for ovarian cancer. About 1 in 10 ovarian cancers (10%) are caused by an inherited faulty gene.

Other possible risk factors include infertility, using HRT, being overweight or tall and having endometriosis.
 

CR PDF Icon You can view and print the quick guides for all the pages in the About ovarian cancer section.

 

 

How common ovarian cancer is

Around 7,300 women are diagnosed with ovarian cancer in the UK each year. This makes ovarian cancer the 5th most common cancer in women, after breast, lung, bowel and womb cancer.

Please note - this information is about risk factors for epithelial ovarian cancer, which makes up almost 9 out of 10 cases of ovarian cancer. We have information about this and the rare types of ovarian cancer in our section on types of ovarian cancer.

 

What risk factors are

A risk factor is anything that can increase your chance of developing cancer. Different cancers have different risk factors. Some factors can lower your risk of cancer and are known as protection factors.

 

Factors that may increase ovarian cancer risk

We don't know exactly what causes epithelial ovarian cancer. But some factors may increase the risk. Other factors seem to reduce it and are listed at the bottom of this page. 

Many factors seem to be related to how the ovaries work. When one of your ovaries produces an egg (ovulation), the surface layer of the ovary bursts to release the egg. The surface cells then divide to repair the damage. The more eggs your ovaries produce during your life time, the more cells need to divide and the higher the chance that damage will occur that could lead to cancer. 

There is more about this in our section about how cancers start.

The risk of ovarian cancer may be increased by the following factors.

 

Getting older

As with most cancers, the risk of developing ovarian cancer increases as you get older. Most cases are in women who have had their menopause.

 

Inherited faulty genes

Most ovarian cancers are due to gene changes that develop during a woman’s life and are not inherited. But about 1 in 10 ovarian cancers (10%) are caused by an inherited faulty gene. Faulty inherited genes that increase the risk of ovarian cancer include BRCA1 and BRCA2. These genes also increase the risk of breast cancer.

Read more about family history and inherited cancer genes.

If you are worried about your family history of ovarian cancer, speak to your GP. They can tell you whether you need a referral to a genetics service. 

If you would like to check your own breast or ovarian cancer risk you can use the OPERA online interactive tool.

 

Previous breast cancer

Breast cancer and ovarian cancer can sometimes be due to the same faulty genes. Women who have had breast cancer have up to double the risk of developing ovarian cancer compared to other women in the population, and if their breast cancer was diagnosed before the age of 40, their risk is even higher.

If you think you may have a faulty gene, you can speak to your GP. There is more information about screening for ovarian cancer in this section.

 

Being infertile or having fertility treatment

Some older studies showed a link between taking fertility drugs and an increased risk of ovarian cancer. But more recent research doesn't support this. A 2013 Cochrane review looked at the risk of ovarian cancer in women who took fertility drugs. The reviewers found no strong evidence that women who took fertility drugs had an increased risk of ovarian cancer. But there may be an increased risk of borderline ovarian tumours in infertile women treated with IVF. You can read this review on fertility drugs and ovarian cancer risk in the Cochrane library. It was written for researchers and specialists so it is not in plain English. 

It is more likely that infertility itself increases ovarian cancer risk, rather than fertility treatment being the cause. More research is going on to try to clarify this.

 

Using hormone replacement therapy (HRT)

In the UK, less than 1 in 100 (1%) of ovarian cancers are linked to hormone replacement therapy (HRT) use. 

You can read more about HRT and cancer in our section about the causes of cancer

 

Being overweight or tall

Researchers looked at the risk of being overweight in premenopausal and postmenopausal women. They found that the risk of ovarian cancer was higher in premenopausal women with a BMI above 28, but there was no effect in postmenopausal women. 

Ovarian cancer risk is higher in women who have a high BMI and have never used HRT. Women who have a high BMI and have used HRT have a lower risk of developing ovarian cancer. 

Research has also found that taller women have a higher risk of ovarian cancer than shorter women.

 

Having endometriosis

Research has shown that women with endometriosis have an increase in their ovarian cancer risk compared to women who do not.  

 

Using talcum powder

Using talcum powder between your legs is thought to increase the risk of ovarian cancer. The powder could, in theory, travel up into the vagina and then through the cervix into the womb. If it then worked its way down the fallopian tubes to the ovaries, it could get into the ovaries themselves and cause irritation. Constant irritation could potentially cause inflammation and lead to cancerous changes in cells. 

 

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. 

For other types of ovarian tumours, such as clear cell and ovarian endometriod cancer, there was a variation in how much smoking affected risk. 

 

Diet factors

There has been a lot of research into the effect of dietary factors on ovarian cancer risk and so far most findings have been inconclusive and inconsistent. This may be because there is either no link between diet and ovarian cancer, or it is very small. Or it might be because of problems with the design of the studies.

Some studies have shown that a diet high in fats, particularly animal fats, may increase your risk of ovarian cancer. But more research is needed before we know whether changing our diet can reduce the risk of ovarian cancer. 

 

Protection factors for ovarian cancer

Your risk of ovarian cancer may be lowered by

Taking the contraceptive pill

Taking the 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 come down. The reduction in risk lasts for at least 30 years after you stop taking the pill.

Having children

Having children seems to reduce the risk of ovarian cancer. The more children a woman has the lower the risk. 

Breast feeding

Breastfeeding might lower the risk of ovarian cancer. This may be because your ovaries normally stop producing eggs each month while you are breastfeeding.  

A meta-analysis has shown that women who breastfed have a lower risk of getting ovarian cancer compared with women who never breastfed. The risk was lower in women who breast fed for a longer time. 

Having a hysterectomy or having your tubes tied

Having your tubes tied because you don't want any more pregnancies is called sterilisation. Two recent meta-analysis studies combined the results from all of the research looking at this. These studies both 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 newer evidence suggests that there is a higher risk of ovarian cancer for women who have had a hysterectomy in recent years. Researchers think this might be because these days it is less common for younger women to have a hysterectomy. It may also be something to do with a change in the number of women having their ovaries removed, and the use of HRT after hysterectomy. 

Diet

Non-starchy vegetables (such as broccoli, cabbage and onions) may decrease ovarian cancer risk but the evidence is uncertain.

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Updated: 23 March 2016