What is uterine cancer?
Uterine cancer is cancer that begins from abnormal cells in the lining of the uterus (endometrium) or the muscle tissue (myometrium). Uterine cancer is also called cancer of the uterus, womb cancer and cancer of the lining of the womb.
“It’s very rare for uterine cancer to be picked up on a Pap smear. I’d had symptoms, such as nausea and abdominal pain, but I thought they were related to other health conditions I had.”
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The uterus, or womb, is part of a woman’s reproductive system. It is about the size and shape of a hollow, upside-down pear. The uterus sits low in the abdomen between the bladder and rectum and is held there by muscle. It is joined to the vagina by the cervix, which is the neck of the uterus. The uterus is where a foetus grows.
- Myometrium – the outer layer of muscle tissue. This makes up most of the uterus.
- Endometrium – the inner layer or the lining of the uterus. In a woman of child-bearing age, the endometrium changes in thickness each month to prepare for pregnancy.
When a woman releases an egg (ovum) from her ovary (ovulates), the egg travels down her fallopian tube into the uterus. If the egg is fertilised by a sperm, it will implant itself into the lining of the uterus and grow into a baby. If the egg is not fertilised by a sperm, the lining is shed and flows out of the body through the vagina. This flow is known as a woman’s period (menstruation).
Menopause occurs when the levels of hormones in a woman’s body that cause ovulation and menstruation decrease. A menopausal woman’s periods stop, and she is not able to become pregnant. The uterus becomes smaller and the endometrium becomes thinner and inactive.
Types of uterine cancer
The most common type of uterine cancer begins in the lining of the uterus. This is called endometrial cancer. There are two main types of endometrial cancer:
- Type 1 cancer – This is usually called endometrioid cancer. Type 1 cancer is the most common type of endometrial cancer and usually requires less intensive treatment.
- Type 2 cancer – This includes malignant mixed Müllerian tumours, serous carcinoma and clear cell carcinoma. Type 2 cancers are much less common types of endometrial cancer. Treatment usually involves more invasive surgery and chemotherapy and/or radiotherapy.
A less common type of uterine cancer is uterine sarcoma. This develops in the muscle of the uterus (myometrium) or the connective tissue supporting the endometrium, which is called the stroma. There are three types of uterine sarcoma:
- endometrial stromal sarcoma
- undifferentiated sarcoma
These types of uterine cancer are rare and may be more likely to spread to other parts of the body.
Who gets uterine cancer?
About 2300 women in Australia are diagnosed with uterine cancer each year. The majority of uterine cancers are diagnosed in women aged 50 and over. Uterine cancer is the most commonly diagnosed gynaecological cancer in Australia.
What causes uterine cancer?
The exact cause of uterine cancer is unknown, but some factors seem to increase a woman’s risk:
- being aged over 50
- being postmenopausal
- endometrial hyperplasia, a benign condition that occurs when the endometrium grows too thick
- never having children or being infertile
- starting periods early (before age 12)
- reaching menopause late (after age 55)
- having high blood pressure (hypertension)
- having diabetes
- being overweight or obese
- a family history of ovarian, uterine, breast or bowel cancer
- previous ovarian tumours, or polycystic ovary syndrome
- taking oestrogen hormone replacement without progesterone
- previous radiotherapy to the pelvis for cancer
- taking tamoxifen to treat breast cancer. The risk of uterine cancer is usually outweighed by the benefits of treating breast cancer. Talk to your doctor if you are concerned.
Many women who have risk factors don’t develop uterine cancer, and some women who do get cancer have no risk factors.
Visit Cancer Prevention to read about ways to reduce your risk of developing cancer.