What are risk factors?

There are certain things that can increase the risk of developing womb cancer. These are called risk factors. Having a risk factor does not mean you will get cancer. And not having a risk factor does not mean that you will not get it. Most risk factors for womb cancer are linked to how much oestrogen the lining of the womb is exposed to over your lifetime.

If you are worried about womb cancer and would like to talk to someone, we're here. You can:

Age

The risk of womb cancer increases with age.

Hormonal factors

Before the menopause, the ovaries produce the hormones oestrogen and progesterone. These help to control your periods. After the menopause, the ovaries no longer produce hormones, but some oestrogen is still produced by body fat and adrenal glands.

The risk of womb cancer can be affected by:

  • exposure to oestrogen
  • how this is balanced with progesterone.

When there is too much oestrogen without progesterone to balance it, the risk of womb cancer increases.

Longer exposure to oestrogen can increase your risk of womb cancer. This may be influenced by the following factors:

  • Starting your periods early (before the age of 12).
  • Having a late menopause (after the age of 55).
  • Having longer periods.
  • Having irregular periods.
  • Having some type of hormone replacement therapy (HRT), for example oestrogen only HRT.
  • Not having children, or being unable to have children. Oestrogen in the body is low during pregnancy, and the level of progesterone is high.

Weight and physical activity

Being overweight is an important risk factor for womb cancer. After the menopause, body fat is the main source of oestrogen. If you are overweight, you may have a high level of oestrogen.

At least 1 in 3 womb cancers (33%) may be caused by being very overweight (obese). There is also evidence that being less physically active can increase the risk of womb cancer.

Genetic factors (family history)

A small number of womb cancers (fewer than 5 in 100 or less than 5%) are caused by gene changes that are passed on in a family. If there are several close relatives on the same side of the family with bowel, breast, ovarian or womb cancer, there may be a genetic link. Close relatives include parents, children, sisters and brothers.

If you are worried about a family history of cancer, speak to your cancer doctor or GP. They can decide if you should be referred to a family cancer clinic.

There are some genetic conditions that can increase the risk of womb cancer. Women with Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC), have an altered gene that increases the risk of bowel cancer and womb cancer. Women with this gene have a 30 to 60% risk of developing womb cancer over their lifetime. They are screened for bowel cancer and womb cancer. And they may be advised to have a hysterectomy (operation to remove the womb) if they no longer want to be able to get pregnant.

Women with a rare genetic condition called Cowden syndrome have an increased risk of non-cancerous tumours and also some cancers. This includes womb cancer, but the increase in risk is small.

Tamoxifen

Tamoxifen is a hormonal drug used to treat breast cancer. It can slightly increase the risk of pre-cancerous changes in the womb. Rarely, it can cause womb cancer. But there are very clear benefits of taking tamoxifen that far outweigh this risk. Always tell your doctor if you are taking tamoxifen and have any unusual vaginal bleeding.

Other medical conditions

Some other medical conditions may cause an increased risk of pre-cancerous changes in the womb or womb cancer.

Thickening of the womb lining

Thickening of the lining of the womb is called endometrial hyperplasia. Symptoms include heavy periods and bleeding between periods or after the menopause. When it is diagnosed, women have treatment or regular check-ups.

Diabetes

Diabetes increases the risk of womb cancer. There may also be a separate link between womb cancer and insulin, a hormone that regulates blood sugar.

Polycystic ovary syndrome (PCOS)

PCOS is a condition where cysts grow on the ovaries. Women with PCOS may:

  • have fertility problems, infrequent periods or no periods
  • be very overweight or diabetic.

These are all linked with womb cancer risk.

Uncommon ovarian cancers

Some types of ovarian cancers called granulosa and theca cell tumours can produce oestrogen. This increases the risk of pre-cancerous changes and rarely can cause womb cancer.

About our information

  • References

    Below is a sample of the sources used in our womb cancer information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Colombo N et al ESMO-ESGO-ESTRO Consensus Conference on Endometrial Cancer: diagnosis, treatment and follow-up Annals of Oncology 27: 16–41, 2016.

    Sundar S et al BGCS uterine cancer guidelines: Recommendations for practice European Journal of Obstetrics & Gynecology and Reproductive Biology 213 (2017) 71–97.

    RCOG Fertility Sparing Treatments in Gynaecological Cancers 2013.

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Professor Nick Reed, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Content under review

Due to the pandemic, there have been delays in us updating this information as quickly as we would have wanted. Our team is working hard to put this right.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We try to make sure our information is as clear as possible. We use plain English, avoid jargon, explain any medical words, use illustrations to explain text, and make sure important points are highlighted clearly.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected. Our aims are for our information to be as clear and relevant as possible for everyone.

You can read more about how we produce our information here.