Cancer of the uterus

What is cancer of the uterus?

Cancer of the uterus – also called uterine cancer, endometrial cancer, womb cancer, or cancer of the lining of the womb – occurs when cells become abnormal and start growing and multiplying out of control. It can begin in cells in the:

• lining of the uterus (endometrium)
• muscle tissue (myometrium)
• connective tissue (stroma) that supports the endometrium.

Learn more about:

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

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) and vagina (birth canal).

The position of the uterus 

About the size and shape of a hollow, upside-down pear, the uterus sits low in the abdomen between the bladder and rectum. It is joined to the vagina by the cervix. On either side of the uterus are the ovaries, which contain the woman’s 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.

Menstruation 

In a woman of child-bearing age, the endometrium becomes thicker each month to prepare for pregnancy. If no pregnancy occurs, the endometrium is shed and flows out of the woman’s body through the vagina. This flow is known as a woman’s period (menstruation).

Menopause 

The ovaries produce oestrogen and progesterone, the hormones that control the release of eggs (ovulation) and menstruation. During menopause, the levels of these hormones decreases. This means the woman’s ovaries no longer release eggs, her periods stop and she is not able to become pregnant. The uterus becomes smaller and the endometrium becomes thinner.

The female reproductive system

Types of uterine cancer

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

Endometrial cancers

Most cancers of the uterus begin in the lining of the uterus (endometrium) and are called endometrial cancers. There are two main types:

Uterine sarcomas

These are rare soft tissue sarcomas that develop in the muscle of the uterus (myometrium) or the connective tissue (stroma) that supports the endometrium. There are three types: endometrial stromal sarcoma is a low-grade, slow-growing tumour, while leiomyosarcoma and undifferentiated sarcoma are usually faster growing and may be more likely to spread to other parts of the body.

Who gets uterine cancer?

Uterine cancer is the fifth most common cancer in women and the most commonly diagnosed gynaecological cancer in Australia. Each year, about 2700 Australian women are diagnosed with uterine cancer, and most are over 50. About one in 60 women is likely to have uterine cancer by the age of 75.

What causes uterine cancer?

The exact cause of cancer of the uterus is unknown, but some factors seem to increase a woman’s risk:

• being over 50
• being postmenopausal
• having endometrial hyperplasia
• never having children or being unable to have children
• starting periods early (before age 12)
• reaching menopause late (after age 55)
• being overweight or obese and/or having diabetes
• having high blood pressure (hypertension)
• a family history of uterine, ovarian or bowel cancer
• inheriting a genetic condition such as Lynch syndrome or Cowden syndrome
• previous ovarian tumours or polycystic ovary syndrome
• taking oestrogen hormone replacement without progesterone
• previous pelvic radiation for cancer
• taking tamoxifen, an anti-oestrogen drug used for breast cancer (talk to your doctor if you are concerned about this risk).

Many women who have risk factors don’t develop cancer of the uterus, and some women who get cancer have no risk factors.

Other uterine conditions

Other 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 (non-cancerous), although some may eventually turn into cancer. These can be removed during a hysteroscopy and sent to a laboratory for testing.

Fibroids – Benign (non-cancerous) tumours that begin in the muscle layer of the uterus (myometrium). Some women with fibroids choose to have 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 or ovaries. Endometriosis doesn’t lead to cancer, but many women with endometriosis also have endometrial hyperplasia. It may be treated with hormones or surgery.