About the uterus
The pear-shaped uterus is hollow and located in the pelvis of a woman between the bladder and rectum. The uterus is also known as the womb, where a baby grows when a woman is pregnant. It has three sections: the narrow, lower section called the cervix, the broad section in the middle called the isthmus, and the dome-shaped top section called the fundus. The wall on the inside of the uterus has two layers of tissue: endometrium (an inner layer), and myometrium (outer layer), which is muscle tissue.
Every month during a woman's childbearing years, the lining of the uterus grows and thickens in preparation for pregnancy. If the woman does not get pregnant, this thick, bloody lining passes out of her body through her vagina during menstruation. This process continues until menopause, which is when a woman’s ovaries stop releasing eggs.
About uterine cancer
Uterine cancer is the most common cancer of a woman’s reproductive system. Uterine cancer begins when normal cells in the uterus change and grow uncontrollably, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can spread to other parts of the body. A benign tumor means the tumor will not spread. Noncancerous conditions of the uterus include fibroids, which are benign tumors in the muscle of the uterus. Another noncancerous condition is endometriosis, which describes the condition when endometrial tissue, typically lining the uterine cavity, is on the outside of the uterus or other organs. Endometrial hyperplasia, which is an increased number of cells in the uterine lining, can also happen and can be noncancerous.
There are two major types of uterine cancer:
Adenocarcinoma. This makes up more than 80% of uterine cancers. It develops from cells in the lining of the uterus called the endometrium. This cancer is also commonly called endometrial cancer. A common type of endometrial adenocarcinoma is called endometrioid carcinoma, and treatment varies depending on the grade of the tumor, how far it goes into the uterus, and the stage or extent of disease (see Stages and Grades). A less common type is called endometrial serous carcinoma, and this form is treated in a fashion similar to ovarian cancer which is also commonly of the serous type.
Sarcoma. This type of uterine cancer develops in the supporting tissues of the uterine glands or in the myometrium, which is the uterine muscle. Sarcoma accounts for about 2% to 4% of uterine cancers. Sarcomas are treated differently than adenocarcinomas in most situations. Types of endometrial cancers with some elements of sarcoma include leiomyosarcoma, endometrial stromal sarcoma or carcinosarcoma. Learn more about sarcoma.
Cancer specifically in the uterine cervix is treated differently than uterine cancer; learn more about cervical cancer. The rest of this section covers the more common endometrial (adenocarcinoma) cancer.
Looking for More of an Overview?
If you would like additional introductory information, explore the following item. Please note these links take you to other sections on Cancer.Net:
- ASCO Answers Fact Sheet: Read a one-page fact sheet (available in PDF) that offers an easy-to-print introduction to this type of cancer.