There are two hormones produced by the ovaries called oestrogen and progesterone. These hormones control both the growth of the lining of the womb and our periods. The balance between these two hormones helps stop abnormal growths within the lining of the womb. After the menopause the ovaries stop making these hormones. However, some oestrogen is still produced in body fat.
When too much oestrogen is produced without being balanced or “opposed” by progesterone, the risk of developing womb cancer increases. Many of the risk factors linked to womb cancer are associated with a higher level of oestrogen that has not been balanced by progesterone.
Risk factors increase our chance of developing a disease or medical condition, but they do not mean we will or will not develop it. Prevention means things we can do to try and reduce our chance of developing a condition.
Age
The risk of womb cancer increases with age and developing womb cancer is more likely in women over 55 years of age.
Weight and physical activity
Womb cancer is strongly linked to living with overweight or obesity, with around one third of cases being due to excess body fat. After the menopause, body fat is responsible for most of the oestrogen production. Therefore, those who are living with overweight or obesity are more likely to have a higher level of oestrogen in their body that is not balanced with progesterone.
Those who are less active may also have a higher risk of developing womb cancer.
Being physically active is thought to be protective against womb cancer. It can help you stay a healthy weight and can assist in controlling hormones within the body, such as oestrogen and insulin.
Reproductive factors
The following factors have been linked to a possible increased risk of womb cancer as they increase the overall time the body is exposed to oestrogen
- Starting periods at an early age (before age 12)
- Stopping periods at a late age (after age 55)
- Never giving birth to children
- Having difficulties with fertility or not able to have children
- Using a particular type of hormone replacement therapy (HRT) which only contains oestrogen. This is not normally given to women who still have a womb and have not had a hysterectomy.
- Using a drug called tamoxifen which is a hormonal treatment for breast cancer. This is used to stop breast cancer from recurring but there is a small risk of uncontrolled growth of the lining of the womb. When you start tamoxifen, your doctor will discuss this with you. For most women the benefits of reducing the risk of breast cancer outweighs the risk of developing womb cancer so we would not advise you stop this medication without discussion with your breast cancer team. If you take tamoxifen and have any abnormal vaginal bleeding, please seek urgent medical advice.
The following may reduce the risk of developing womb cancer:
- Breastfeeding your children
- Having your last child at a later age
- Using combined hormonal contraception
Medical conditions
Some medical conditions increase the risk of developing womb cancer:
- Polycystic ovary syndrome (PCOS)
PCOS is associated with symptoms such as weight gain, irregular or less frequent periods, acne and facial hair. It causes multiple small cysts to develop in the ovaries. Those diagnosed with PCOS may have less cycles where they produce eggs (ovulation) and are more likely to develop type 2 diabetes, which both increase the risk of womb cancer. - Type 2 diabetes
Type 2 diabetes is a condition where the body becomes more resistant to a hormone called Insulin. Insulin is responsible for controlling the level of sugar in the blood. As the cells in our body are not responding to insulin, the body makes even more insulin to try and help control the sugar. These high levels of insulin and sugar cause the cells in the lining of the womb to grow more and increases the risk of womb cancer.
Family history
We know there are certain inherited conditions that make womb cancer more likely to develop. Inherited conditions are medical conditions that are passed down through families due to changes in genes. Genes are codes or sets of instructions that give our body information on how each cell develops and grows. When this information is changed, it can lead to uncontrolled or cancerous growths in cells. Inherited conditions are more likely where there is a family history of cancer in close relatives such as parents, siblings, and children.
Lynch syndrome
Lynch syndrome may affect up to 175,000 people in the UK and is linked to 3% of cases of womb cancer. To develop Lynch syndrome, you need to have one parent that carries the gene. Someone diagnosed with Lynch syndrome has up to 60% chance of developing womb cancer in their lifetime. Lynch syndrome is also associated with an increased risk of bowel cancer. Those diagnosed with Lynch syndrome undergo regular tests to check for bowel cancer and womb cancer, many will be offered a hysterectomy (operation to remove the womb) to prevent womb cancer once they feel their family is complete.
Lynch syndrome is often diagnosed when a strong family history of bowel or womb cancer is noted. If you feel this may apply to you, please speak to your doctor about being referred to a genetics service. More information on Lynch syndrome can be found here.
Cowden syndrome
Cowden syndrome is a rare condition that causes multiple small benign growths called hamartomas and is also linked to an increased risk of breast, thyroid and womb cancer.
