Cancer of the uterus is the most common of all female reproductive cancers and accounts for approximately 6 percent of all cancers in women in the U.S. Nearly all cancers in the uterus start as endometrial cancer.
The uterus is a hollow, pear-shaped organ located in a woman’s pelvis. Also known as the womb, the uterus is where a baby grows and develops. The walls of the uterus are made up of two layers. The outer layer is muscle called the myometrium. The inner layer or lining of the uterus is a mucus membrane called the endometrium.
During a woman’s monthly cycle, the wall of the endometrium thickens in preparation for an egg to be fertilized and grow during pregnancy. If there is no pregnancy, the endometrium gets thin and sheds out of the body in the woman’s menstrual flow or period.
Risk Factors for Endometrial Cancer
Most endometrial cancers are known as adenocarcinomas, which means the cancer begins in the cells that make and release mucus or other fluids. The cause of endometrial cancer is unclear, but research indicates that increased levels of estrogen may be involved in the process. Risk factors include:
• Age – This cancer occurs most often in menopausal women over age 50, although it has been known to occur in women under 40.
• Endometrial hyperplasia – Women with an increased number of cells in the lining of the uterus may have endometrial hyperplasia. Symptoms of this condition are heavy periods, bleeding between periods, and bleeding after menopause. This condition is not cancer, but it sometimes develops into cancer.
• Hormone replacement therapy (HRT) – Menopausal women may chose to use hormone replacement therapy to reduce the symptoms of menopause. HRT is also used to prevent osteoporosis and to reduce the risk of heart disease. Women who use the hormone estrogen without also using progesterone may be at higher risk of developing cancer.
• Endometrial polyps – A history of benign growths in the uterus may indicate a higher risk of cancer.