Cancer of the uterus

Cancer of the uterus occurs when cells in any part of the uterus become abnormal, grow out of control and form a lump called a tumour. Cancer of the uterus is also called uterine cancer, endometrial cancer, womb cancer, or cancer of the lining of the womb. Endometrial cancer is the most common type of cancer of the uterus. The other main type is the less common uterine sarcoma.

Learn more about:

• Types of uterine cancer
• Who gets uterine cancer?
• What causes uterine cancer?
• Other uterine conditions
• The uterus

Types of uterine cancer

Uterine cancer can be either endometrial cancer (around 95% of all uterine cancers) or the less common uterine sarcoma (around 5% of all uterine cancers).

Endometrial cancers

Cancers that begin in cells in the lining of the uterus (endometrium) are called endometrial cancers. There are two main types:

Uterine sarcomas

These are rare soft tissue sarcomas that develop in the cells in the muscle of the uterus (myometrium) or the connective tissue (stroma) that supports the endometrium. There are three types:

• endometrial stromal sarcoma – mostly low-grade, slow-growing tumours
• leiomyosarcoma – faster-growing and more likely to spread
• undifferentiated sarcoma – faster-growing and more likely to spread.

For more on this, see Soft Tissue Sarcoma.

Who gets uterine cancer?

Each year, about 3200 Australian women are diagnosed with uterine cancer, and most are over 50. Uterine cancer is the fifth most common cancer in women and the most commonly diagnosed gynaecological cancer in Australia. (Cancers that affect the female reproductive system are known as gynaecological cancers.)

The number of women diagnosed with uterine cancer has increased in recent years, and includes younger women. This increase is likely to be due to rising rates of obesity and diabetes.

Anyone with a uterus can get uterine cancer – women, transgender men and intersex people. For information specific to your situation, speak to your doctor.

What causes uterine cancer?

The exact cause of cancer of the uterus is unknown, but factors that can increase the risk include:

• age – uterine cancer is most common in women over 50 and in women who have stopped having periods (postmenopausal)
• body weight – being overweight or obese is a major risk factor; the higher your body mass index (BMI), the greater the risk
• medical factors – having diabetes; having previous pelvic radiation therapy for cancer; having endometrial hyperplasia
• family history – having one or more close blood relatives diagnosed with uterine, ovarian or bowel cancer; or inheriting a genetic condition such as Lynch syndrome or Cowden syndrome
• reproductive history – not having children
• hormonal factors – starting periods before the age of 12; going through menopause after the age of 55; taking some types of oestrogen-only menopause hormone therapy (MHT), previously called hormone replacement therapy (HRT); or taking tamoxifen, an anti-oestrogen drug used for breast cancer.

Many women who have risk factors don’t develop cancer of the uterus, and some women who get this cancer have no risk factors. If you are concerned about any risk factors, talk to your doctor. Maintaining a healthy body weight and being physically active are the best ways to reduce the risk of developing cancer of the uterus.

Other uterine conditions

Some conditions can affect the uterus and cause abnormal vaginal bleeding and pain. They may be found during tests for uterine cancer.

Polyps – Small, soft growths attached to the inner wall of the uterus. Polyps are usually benign (not cancer), although some may eventually turn into cancer. These can be removed during a hysteroscopy and sent to a laboratory for testing.

Fibroids – Benign tumours that begin in the muscle layer of the uterus (myometrium). They may be treated with surgery to remove the uterus (hysterectomy).

Endometrial hyperplasia – Thickening of the lining of the uterus (endometrium) caused by too much oestrogen. It is usually benign, but in some cases can lead to cancer, so may be treated with hormones or minor surgery.

Endometriosis – When endometrial tissue grows outside the uterus, e.g. in the abdomen. It doesn’t lead to cancer, but many people also have endometrial hyperplasia. Endometriosis may be treated with hormones or surgery.

The uterus

The uterus, or womb, is where a baby grows during pregnancy. It is part of the female reproductive system, which also includes the ovaries, fallopian tubes, cervix (neck of the uterus), vagina (birth canal) and vulva (external genitals).

The shape and position in the body 

The uterus is about the size and shape of a hollow, upside-down pear. It sits low in the abdomen (belly) between the bladder and rectum, and is joined to the vagina by the cervix. On either side of the uterus are the ovaries, which contain eggs (ova). The ovaries are connected to the uterus by the fallopian tubes.

The layers of the uterus 

The uterus has two layers. The myometrium is the outer layer of muscle tissue and makes up most of the uterus. The endometrium is the inner layer or lining.

The female reproductive system

Menstruation 

Each month, from puberty to menopause, the endometrium becomes thicker to prepare for pregnancy. If no pregnancy occurs, some of the lining is shed and flows out of the body through the vagina. This flow is known as a monthly period (menstruation).

Menopause 

The hormones oestrogen and progesterone control the release of eggs (ovulation) and the timing of menstruation. As you get older, the ovaries gradually produce less of these hormones. When the levels of oestrogen and progesterone fall low enough, periods become irregular and finally stop. This is known as menopause. After menopause, you can’t conceive a child naturally. The uterus also becomes smaller and the endometrium becomes thinner.