What is endometrial cancer?
Cancer starts when cells in the body begin to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body. To learn more about how cancers start and spread, see What Is Cancer?
Endometrial cancer starts in the inner lining of the womb (uterus). This lining is called the endometrium. The picture below shows where the uterus is found.
The uterus (womb) is a hollow organ, which is normally about the size and shape of a medium-sized pear. When a woman is pregnant, the fetus grows in the uterus. There are 2 main parts:
- The lower part of the uterus, which extends into the vagina, is called the cervix.
- The upper part is the body of the uterus (also called the corpus).
The body of the uterus has 2 layers. The inner layer is the endometrium. The outer layer of muscle is known as the myometrium. This thick layer of muscle is needed to push the baby out during birth. The tissue coating the outside of the uterus is the serosa.
Types of cancers of the uterus and endometrium
Nearly all cancers of the uterus start in the endometrium. They are called endometrial carcinomas. Cancers can also start in the muscle layer of the uterus. These cancers belong to the group of cancers called sarcomas and are covered in Uterine Sarcoma.
Cancers that start in the cervix are different from cancers that start in the body of the uterus. They are described in Cervical Cancer.
Cancers that start in the cells that line organs in the body are called carcinomas. Most endometrial cancers are not just carcinomas they are adenocarcinomas. This is a type of carcinoma that starts in the cells lining glands – such as the glands that line the uterus. The most common type of adenocarcinoma of the uterus is called endometrioid adenocarcinoma. There are other types that are far less common.
The grade of an endometrioid adenocarcinoma is based on how much the cancer cells form glands that look like the glands found in normal, healthy endometrium (such as the glands that produce the lining that is shed monthly as a “period”). In lower-grade cancers (grades 1 and 2), more of the cancer cells form normal-looking glands. In higher-grade cancers (grade 3), more of the cancer cells are kind of jumbled up and do not form normal glands. Higher grade cancers tend to grow faster and are more likely to spread than lower-grade cancers.
Uterine carcinosarcoma (CS) is another cancer that starts in the endometrium and is covered here. When looked at under the microscope, this cancer looks like both endometrial carcinoma and sarcoma. It acts much like a high-grade adenocarcinoma and is treated much the same way.
Last Medical Review: 02/09/2015
Last Revised: 02/04/2016