The uterus, or womb, is where a baby grows during pregnancy. The uterus is about the size and shape of a hollow, upside-down pear.
It is part of the female reproductive system and sits low in the abdomen, 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. The ovaries are connected to the uterus by the fallopian tubes.
The uterus has two layers. The myometrium is the outer layer of muscle tissue and makes up most of the uterus, and the endometrium is the inner layer or lining.
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Types of 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 can be either endometrial cancer or the less common uterine sarcoma:
Endometrial cancers (around 95% of all uterine cancers)
Cancers that begin in cells in the lining of the uterus (endometrium) are called endometrial cancers. There are two main types:
- type 1 cancers (linked to an excess of oestrogen) are the most common endometrial cancers. Most are adenocarcinomas, which start in glandular cells. They usually grow slowly and are less likely to spread.
- type 2 cancers (not linked to oestrogen) are much less common, but grow faster and are more likely to spread. They include uterine carcinosarcomas, serous carcinomas and clear cell carcinomas.
Uterine sarcomas (around 5% of all uterine cancers)
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.
Other uterine conditions
Some conditions can affect the uterus and cause abnormal vaginal bleeding and pain. They may be found during tests for cancer of the uterus and can be treated in different ways including surgery and hormones.
- 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.
- Fibroids – Benign tumours that begin in the muscle layer of the uterus (myometrium).
- 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.
- 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.
How common is it?
Each year, about 3,200 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.
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.
The most common symptom of cancer of the uterus is unusual vaginal bleeding. This may include:
- a change in your periods
- heavier than usual periods
- bleeding between periods
- constant bleeding (periods that continue without a break)
- bleeding or spotting after menopause.
A less common symptom is a smelly, watery vaginal discharge. In rare cases, symptoms include abdominal pain, unexplained weight loss, difficulty urinating or a change in bowel habit.
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.
- medical factors – including having diabetes, having previous pelvic radiation therapy for cancer and 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 – including 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) 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. Maintaining a healthy body weight and being physically active are the best ways to reduce the risk of developing cancer of the uterus.
Understanding Cancer of the Uterus
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Expert content reviewers:
A/Prof Jim Nicklin, Director, Gynaecological Oncology, Royal Brisbane and Women’s Hospital, and Associate Professor Gynaecologic Oncology, The University of Queensland, QLD; Dr Robyn Cheuk, Senior Radiation Oncologist, Royal Brisbane and Women’s Hospital, QLD; Prof Michael Friedlander, Medical Oncologist, The Prince of Wales Hospital and Conjoint Professor of Medicine, The University of NSW, NSW; Kim Hobbs, Clinical Specialist Social Worker, Gynaecological Cancer, Westmead Hospital, NSW; Adele Hudson, Statewide Clinical Nurse Consultant, Gynaecological Oncology Service, Royal Hobart Hospital, TAS; Dr Anthony Richards, Gynaecological Oncologist, The Royal Women’s Hospital and Joan Kirner Women’s and Children’s Hospital, VIC; Georgina Richter, Gynaecological Oncology Clinical Nurse Consultant, Royal Adelaide Hospital, SA; Deb Roffe, 13 11 20 Consultant, Cancer Council SA.
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The information on this webpage was adapted from Understanding Cancer of the Uterus - A guide for people with cancer, their families and friends (2021 edition). This webpage was last updated in June 2021.