Most cases of uterine cancer arise from the inside lining of the uterus (the endometrium). This is called endometrial cancer. The most common early symptom is abnormal vaginal bleeding.
The uterus (womb) is in the lower abdomen behind the bladder. The inside of the uterus is where a baby grows if you become pregnant. The inside lining of the uterus is called the endometrium. This builds up and is then shed each month as a period in women who have not yet gone through the menopause. The thick body of the uterus is called the myometrium and is made of specialised muscle tissue. The lowest part of the uterus is called the cervix (the neck of the womb) which pushes just into the top part of the vagina. At the top of the womb are the right and left Fallopian tubes which carry the eggs (released from the ovaries) to inside the womb.
Most uterine cancers develop from cells in the endometrium (endometrial cancer). Cancer developing from muscle cells in the myometrium (uterine sarcomas) are rare and are not dealt with further in this leaflet. Cervical cancer (cancer of the cervix) is quite different to uterine cancer and is dealt with in a separate leaflet.
The rest of this leaflet deals only with endometrial cancer of the uterus.
Type and grade of endometrial cancer
Most cases of endometrial cancer are called endometrioid adenocarcinomas. These arise from cells which form the glandular tissue in the lining of the endometrium. A sample of cancer tissue can be looked at under the microscope. By looking at certain features of the cells the cancer can be graded.
There are also some rarer types of endometrial cancer.
A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply out of control. See separate leaflet called What causes cancer? for more details.
There are risk factors which are known to increase the risk of endometrial cancer developing. These include the following:
Increased exposure to oestrogen. Oestrogen is the main female hormone. Before the menopause the changing level of oestrogen together with another hormone, progesterone, cause the endometrium to build up each month and then be shed as a period. It is thought that factors which lead to prolonged higher than usual levels of oestrogen, or increased levels of oestrogen not being balanced by progesterone, may somehow increase the risk of endometrial cells becoming cancerous. These include:
In most cases the first symptom to develop is abnormal vaginal bleeding such as:
Early symptoms that occur in some cases are: