Causes and risk factors
The exact cause of uterine cancer is unknown, though there are certain factors that can increase a woman's risk of developing it. Just because someone has a risk factor does not mean they will have cancer, and not having a risk factor does not mean they will not develop cancer.
Most risk factors are linked to the amount of estrogen the endometrium is exposed to.
The risk of uterine cancer increases with age.
Before menopause, the ovaries produce hormones such as estrogen and progesterone which help control menstrual cycles. After menopause, the ovaries produce a drastically lower level of hormones, though women still maintain their estrogen levels, mainly in body fat. Women's exposure to estrogen and the way it is balanced with progesterone affect the risk of developing uterine cancer.
Prolonged estrogen exposure may increase the risk. Factors influencing this:
- Start of menstruation (menarche) at a very young age
- Late menopause
- Irregular menstrual cycles
- amenorrhea (prolonged absence of menstruation during childbearing age)
- hormone replacement therapy (HRT)
- Estrogen-only HRT (without progesterone)
- Not having children. Estrogen levels are low during pregnancy, which is when progesterone levels increase.
Bodyweight and physical activity
Being overweight is an important risk factor for uterine cancer. After menopause, body fat is the main source of estrogen.
Women who are overweight may have a high estrogen level. One of every three cases of uterine cancer may be caused by being overweight. There is also evidence that lower physical activity can increase the risk of having uterine cancer.
Genetic factors (family history)
A very small number of uterine cancers may be caused by changes to a particular gene. Genes store the biological information we inherit from our parents. If there are several close relatives on the same side of the family with colon, breast, or uterine cancer, there is a chance that there is a genetic relation. Your close family members include your parents and siblings.
There are some genetic conditions that can increase the risk of uterine cancer. Women with Lynch syndrome, also called hereditary nonpolyposis colorectal cancer (HNPCC) have an altered gene that increases the risk of colon and uterine cancer. Women with this genetic condition have a 30 to 60% chance of developing cancer of the uterus throughout their life.
Women with a genetic condition called Cowden syndrome have an increased risk of benign (noncancerous) tumors and also some types of cancer. These include uterine cancer, though the risk is small.
Tamoxifen is a hormone therapy used to treat breast cancer. Taking tamoxifen over a long period of time can cause a slight increase in the risk of uterine cancer. The benefits of taking tamoxifen far outweigh this risk. Always let your doctor know if you are taking tamoxifen or if you have any unusual vaginal bleeding.
Thickening of the womb lining
Endometrial hyperplasia is a condition where the lining of the uterus thickens. The symptoms include heavy menstrual flow and bleeding between period or after menopause.
Diabetes increases the risk of uterine cancer in women. There may also be a link between uterine cancer and insulin, a hormone that regulates blood sugar.
Polycystic ovary syndrome (PCOS)
Women with PCOS may have fertility problems, having very infrequent periods or no period at all or be overweight or diabetic. These are all linked with womb cancer risk.
Many of these risk factors are beyond our control. However, maintain a healthy weight and staying more physically active can help reduce the risk of uterine cancer.