Endometrial cancer (womb cancer)
What is cancer of the womb?
The most common cancer of the womb in the UK is endometrial cancer, also known as uterine cancer.
Various conditions, both benign and cancerous (malignant), can affect the uterus, the hollow, pear-shaped organ in which a baby grows. Fibroid tumours on the uterine wall are benign (non- cancerous), and women who have them are not at increased risk of womb cancer. Abnormal growth of cells in the lining of the uterus - called the endometrium - is known as endometrial hyperplasia. It is the most serious benign uterine condition and in some women it evolves into womb cancer.
Most cancers of the womb arise in the endometrium and are called endometrial cancer or endometrial carcinoma. A more aggressive form, uterine sarcoma, develops in the wall of the uterus and accounts for fewer than 5% of all cases.
If left untreated, womb cancer can penetrate the wall of the uterus and invade the bladder or rectum, or it can spread to the vagina, fallopian tubes, ovaries and more distant organs. Fortunately, cancer of the womb grows slowly and is usually detected before spreading very far.
What causes womb cancer?
Womb cancer is a disease of older (usually post- menopausal) women. More than 95% of these cancers occur in women over the age of 40, with an average age of 63 years at the time of diagnosis. Post-menopausal women are at high risk of endometrial cancer if they:
- Began menstruating early
- Went through the menopause late
- Are overweight/obese
- Have diabetes
- Do little physical activity
- Have few or no children
- Have a history of infertility, irregular menstrual periods or endometrial hyperplasia
Women taking the drug Tamoxifen to treat breast cancer are at a very slightly increased risk of womb cancer, however, this risk is outweighed by the benefit tamoxifen provides in preventing breast cancer.
Women who have taken contraceptive pills are less likely to develop the disease after menopause as those who have not.
The risk of womb cancer is linked to the amount of the female hormone oestrogen the endometrium has been exposed to during the woman's lifetime, since oestrogen stimulates cell formation. Women who have had a long span of menstruation have a higher risk of womb cancer.
Modern post-menopausal hormone replacement therapy (HRT) contains very low doses of oestrogen and progesterone, another female hormone that suppresses cell formation. Women using oestrogen only without progesterone have an increased risk of womb cancer. This is why oestrogen-only HRT is only recommended for those women who have had a hysterectomy.
Rare ovarian tumours can produce oestrogen and increase a woman’s chance of developing cancer of the uterus.
Being overweight increases the risk of womb cancer by two to three times, and being obese increases the risk by a factor of up to six. This is because being overweight and obese increases the amount of oestrogen in the body.