During the reproductive phase in women, starting from menarche until menopause, ovaries produce estrogen and progesterone that bring about cyclic changes in the endometrium.
Any disturbance in the balance between the two hormones (especially a shift towards more estrogen) increases the risk of endometrial cancer. Prolonged exposure to estrogen is the single most important risk factor which is found associated with endometrial cancer.
Risk factors are the inherited or acquired factors that increase the chance of developing cancer in a person. Several epidemiological studies have suggested a number of genetic and environmental factors that may predispose to endometrial cancer. A knowledge about them helps us to make necessary lifestyle choices.
Following is a list of such risk factors for endometrial cancer:
- Early menarche/late menopause: Commencement of menstrual cycles (menarche) at an early age or cessation of menstrual cycles (menopause) at a later age than normal have been reported to elevate the risk of developing endometrial cancer. The increased risk is postulated to be related to the longer duration of exposure to the estrogen.
- Nulliparity: Women who never carried a full-term pregnancy are considered to be at higher risk of developing endometrial cancer probably due to the protective effect of pregnancy that shifts the hormonal level towards more progesterone.
- Hormone replacement therapy: Treating menopause symptoms like hot flashes, vaginal dryness, and osteoporosis with hormones especially estrogen alone (without progesterone) may lead to increased risk of endometrial cancer by about fivefold.
- Tamoxifen therapy: Tamoxifen is used to prevent or treat breast cancer in some patients which act as an anti-estrogen for breast cells but as a weak estrogen for endometrium. Thus, use of tamoxifen in breast cancer can increase the risk of developing endometrial cancer.
- Radiation exposure: Women with a history of radiation treatment for pelvis (maybe for the treatment of other cancer like cervix or colorectal cancer) are at increased risk of developing endometrial cancer.
- Ovarian disorders: Certain ovary disorders like polycystic ovarian syndrome (PCOS) and certain ovary tumors can lead to an abnormally high level of estrogen. Such a high level of estrogen increases the risk of developing endometrial cancer.
- Obesity: Overweight or obese women are at higher risk of developing endometrial cancer which may be due to a higher exposure to estrogen that is produced by the fat tissue after menopause.
- Family history: Risk of developing endometrial cancer increases in females with a history of endometrial cancer in close relatives.
- Genetic alterations: Certain inherited genetic alterations have been reported to be associated with a high incidence rate of endometrial cancer, for example (e.g.), Lynch syndrome (or hereditary nonpolyposis colon cancer [HNPCC] caused due mutation in genes: MLH1, MLH3, MSH2, MSH6, TGFBR2, PMS1, and PMS2.
- Older age, consumption of a high-fat diet, lack of physical activity and longer sitting hours are other risk factors for endometrial cancer. Hypertension and diabetes may be secondary to obesity but they have been reported to raise the risk of endometrial cancer.
Apart from the above-listed risk factors, certain protective factors which can reduce the risk of endometrial cancer have also been identified. Such protective factors mainly include full-term pregnancy, multiparity (multiple pregnancies), use of an intrauterine device, and oral contraceptives use for birth control.
In the next section, you will read about the symptoms of endometrial cancer.
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