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Each year, about 7000 women in the UK are diagnosed with cancer of the womb. The cause in most women is still unknown, but research is going on to try to find it.
Many of the risk factors associated with womb cancer are related to the body’s exposure to the female hormone oestrogen in balance with the female hormone progesterone. Too much oestrogen exposure without progesterone will increase the risk of womb cancer. Other possible risk factors include age, obesity and the use of oestrogen-only hormone replacement therapy (HRT).
Other factors (called protective factors) may reduce a woman’s risk of womb cancer, such as having children.
A risk factor is something that increases your chance 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 doesn’t mean you definitely will get cancer, just as people without any known risk factors can develop cancer.
Like most types of cancer, womb cancer is more common in older people. Over 90% (9 in 10) of womb cancers are diagnosed in women over 50. Womb cancer rarely affects women under 35.
Being overweight is an important risk factor for developing womb cancer. Fatter women tend to have higher levels of oestrogen. This is because fat cells in the body create a form of oestrogen. The more overweight or obese you are, the greater your risk of developing womb cancer. As many as four out of ten womb cancers may be caused by obesity.
Your risk of developing womb cancer reduces if you have had a baby. You are more likely to develop womb cancer if you have never been pregnant. During pregnancy the level of oestrogen in the body is low and the level of progesterone is high.
Research suggests that women who have had three children may reduce their risk of developing womb cancer by as much as two-thirds.
A woman’s risk of womb cancer may be influenced by her periods (menstruation). This is because the period will change the level of oestrogen in the body. Factors that might increase the risk of womb cancer are:
There are different types of hormone replacement therapy (HRT). Oestrogen-only HRT can increase the risk of womb cancer. It is usually only given to women who have had their womb removed.
Women who have not had their womb removed are usually given a combination of the hormones oestrogen and progesterone, rather than oestrogen on its own. Taking combined oestrogen and progesterone HRT for up to five years doesn’t increase the risk of developing womb cancer, but if it’s taken for more than five years the risk may be slightly increased. Combined HRT can slightly increase the risk of breast cancer, so women should discuss the risks and benefits carefully with their doctor.
Women who take the contraceptive pill are thought to have a lower risk of developing womb cancer.
Most womb cancers are not caused by a faulty gene| that runs in a family. But, if you have several close relatives on the same side of the family who’ve had bowel| or womb cancer you may be at increased risk of womb cancer yourself. There may be a faulty gene running in your family that you were born with. However, even if there is a faulty gene in your family, you may not have inherited it.
If you are concerned about a family history of womb cancer, you can talk to your GP about your family history and whether it would be helpful to see to a genetic counsellor at a family cancer clinic, or a cancer specialist.
The inherited faulty gene called HNPCC (hereditary non-polyposis colorectal cancer)| increases the risk of developing a variety of cancers, especially bowel (colorectal) cancer. It can also increase the risk of womb cancer. Approximately 60% (6 in 10) of women who have the HNPCC gene will develop womb cancer. If you have several relatives who have had bowel or womb cancer and are worried about the possibility of HNPCC in your family, talk to your GP. Families with HNPCC are often closely monitored for signs of cancer so that it can be treated in the very early stages.
Taking tamoxifen| (a hormonal therapy sometimes taken to treat breast cancer|) over a long period of time can slightly increase the risk of developing womb cancer. However, the benefits of taking tamoxifen to treat breast cancer are considered to outweigh the risk.
Having polycystic ovary syndrome (PCOS), in which cysts grow on the ovaries, may slightly increase the risk of womb cancer. Symptoms of PCOS include infertility problems, infrequent periods or no periods at all.
Women who have endometrial hyperplasia may also have an increased risk of womb cancer. This is a condition where the lining of the womb becomes thicker than normal. Symptoms include heavy periods and bleeding between periods or after the menopause.
A rare condition called Cowden’s syndrome, where lots of benign (non-cancerous) tumours can develop in the body, may slightly increase the risk of a number of different cancers including womb cancer.
Having diabetes may also increase a women’s risk of developing womb cancer.
Womb cancer, like other cancers, is not infectious and can’t be passed on to other people.
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.