What Is Endometrial Cancer

What Is Endometrial Cancer?
Endometrial cancer starts when cells in the endometrium (the inner lining of the uterus) start to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other parts of the body. To learn more about how cancers start and spread, see What Is Cancer?

About the uterus and endometrium
The uterus is a hollow organ, normally about the size and shape of a medium-sized pear. The uterus is where a fetus grows and develops when a woman is pregnant. It has 2 main parts (see image below):

The upper part of the uterus is called the body or the corpus. (Corpus is the Latin word for body.)
The cervix is the lower end of the uterus that joins it to the vagina.
When people talk about cancer of the uterus, they usually mean cancers that start in the body of the uterus, not the cervix. (Cervical cancer is a separate kind of cancer.)


illustration showing the female reproductive organs including location of uterine cavity, endometrium, myometrium, serosa, fallopian tubes, ovaries, body of the uterus, endocervix, exocervix, cervix and vagina
The body of the uterus has 2 main layers:

The myometrium is the outer layer. This thick layer of muscle is needed to push the baby out during birth.
The endometrium is the inner layer. During a woman's menstrual cycle, hormones cause the endometrium to change. Estrogen causes the endometrium to thicken so that it could nourish an embryo if pregnancy occurs. If there is no pregnancy, estrogen is produced in lower amounts and more of the hormone called progesterone is made. This causes the endometrial lining to shed from the uterus and become the menstrual flow (period). This cycle repeats until menopause.
There is also a layer of tissue called the serosa which coats the outside of the uterus.

Types of endometrial cancer
Endometrial cancer (also called endometrial carcinoma) starts in the cells of the inner lining of the uterus (the endometrium). This is the most common type of cancer in the uterus

Endometrial carcinomas can be divided into different types based on how the cells look under the microscope. (These are called histologic types.) They include: