Cancer of the endometrium (the inner lining of the uterus) is a common cancer affecting the female reproductive tract, and is diagnosed in around 6,000 women each year in the UK. The disease most commonly affects women between the ages of 55 and 65, and typically causes vaginal bleeding or a bloody discharge. More than three quarters of cases are diagnosed early, and the standard treatment is the removal of the uterus and both ovaries.
It is thought that the risk of endometrial cancer increases if the uterus is exposed to oestrogen without a balancing level of progesterone. This unopposed oestrogen may produce overgrowth of the endometrium (hyperplasia), leading to less regulation of cell growth. Endometrial hyperplasia may itself produce abnormal vaginal bleeding and may be detected in much the same way as endometrial cancer (see below). The risk of developing cancer depends upon the type of hyperplasia:
Women with cystic glandular hyperplasia or complex typical hyperplasia have around a one percent risk of developing endometrial cancer.
Women with complex atypical hyperplasia have a 10-20% risk of developing endometrial cancer.
Risk factors for endometrial hyperplasia and cancer include being pre-menopausal but not ovulating1, taking oestrogen-only hormone replacement therapy (HRT)2 or the breast cancer drug tamoxifen, having a family history of non-polyposis colorectal cancer, having a delay in the menopause beyond the age of 55, being overweight, and having high blood pressure. Women with long-standing polycystic ovarian syndrome have an increased risk of endometrial cancer due to a lack of progesterone production.
Symptoms and Diagnosis
The common symptoms are irregular vaginal bleeding or a small bloody discharge – these most often occur in post-menopausal women – though a few women may have a watery discharge instead. If a tumour grows towards the bottom of the uterus, it may block the cervix3 and cause fluid or pus to accumulate inside the uterus, leading to a palpable swelling.
Any menopausal or post-menopausal woman with irregular bleeding or bloody discharge should be investigated for endometrial cancer. The thickness of the endometrium can be measured using a transvaginal ultrasound – this can exclude cancer if the endometrium is thin, but does not necessarily prove the presence of cancer if the endometrium is thick. In women with a thickened endometrium, the inside of the uterus is inspected using a hysteroscope4, following which the cervix is dilated and a biopsy curette (a sharp scoop) is rotated inside the uterus in order to obtain a tissue sample. Women with an endometrium less than 5mm thick usually have a cervical smear taken and have a tissue sample taken without hysteroscopy.
Staging and Prognosis
As endometrial cancer tends to grow across the endometrium before breaking through to the layers below, more than three quarters of cases are diagnosed early. The prognosis depends upon the stage of the disease, and so the percentage surviving for more than five years following treatment is provided in brackets below for each stage.
- IA – limited to the endometrium (90%).
- IB/IC – invasion of less than/more than half of the myometrium5 (80%).
- II – invasion of the cervix (70%).
- III – invasion of tissues surrounding the uterus (40%).
- IVA/IVB – invasion of the bladder or bowel/distant spread (10%).
Regardless of the stage, endometrial cancer is generally treated by a total removal of the uterus (hysterectomy) and both the ovaries (bilateral oopherectomy) once the cancer has been staged using MRI and laparoscopy6. In women who cannot undergo an operation, progesterone treatment may be used as a substitute. Women with stage IC or worse are given radiotherapy to the vagina and pelvis in order to treat any tumour that has spread beyond the uterus. Women with stage IV cancer are provided with palliative surgery to relieve symptoms along with radiotherapy, progesterone therapy and chemotherapy with agents such as cisplatin.
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1 Ovulation is the part of the menstrual cycle in which an egg is normally released by an ovary.
2 The combined pill and combined oestrogen and progesterone HRT do not increase the risk of endometrial cancer, though the HRT tibolone is an exception as it does lead to an increased risk.
3 The neck of the womb.
4 A camera that is inserted into the uterus via the vagina.
5 The muscular part of the uterus that lies just outside the endometrium.
6 Laparoscopy involves the use of several small 'keyhole' cuts through which a camera and surgical instruments can be passed.