Cancer happens when cells in your body go through changes that make them grow out of control. Endometrial cancer starts in the inner lining of the uterus called the endometrium.
The uterus is part of the female reproductive system. The uterus is usually pear-shaped and about the size of a fist. It is located in your pelvic area, between your bladder and your rectum. Your uterus is connected to your fallopian tubes, which help carry the egg from your ovary into the uterus. The small opening that connects the uterus to your vagina is the cervix. The uterus consists of 3 layers:
Endometrium. This is the inner lining.
Myometrium. This is the middle muscle layer.
Serosa. The is the outer smooth layer.
In women who still have their periods, one ovary releases an egg into a fallopian tube each month. During this time, the endometrium becomes thicker in preparation to receive a fertilized egg. If the egg connects with a male sperm cell, however, this fertilized egg attaches to the endometrium. The uterus protects the growing fetus during pregnancy. During labor, the myometrium, or muscle tissue, helps push the baby out through the cervix. The smooth serosa makes it easy for the uterus to move in the pelvis as needed.
Endometrial cancer usually takes years to develop. It most often occurs in women who have already gone through menopause.
This article refers to endometrial cancer, but other kinds of cancer can form in the uterus as well. These are called uterine sarcomas.