Uterine (Endometrial) Cancer

Overview and Staging

The uterus is a hollow organ about the size and shape of a pear. When a woman is pregnant, the fetus grows in the uterus, which is also referred to as the womb. The uterus has two main parts: the cervix, which is the “neck” of the uterus that extends into the vagina, and the upper part, or the body or corpus of the uterus.

The main type of cancer of the uterus is called endometrial cancer. It starts in the cells of the endometrium, the inner lining of the uterus. Endometrial cancer is the most common gynecologic cancer. Although the cervix is part of the uterus, cancer that occurs in the cervix is called cervical cancer and is not the same as endometrial cancer.

Diagnosing and staging

The results of an endometrial biopsy allow your doctor to diagnose endometrial cancer. After cancer has been diagnosed, it is staged. In staging cancer, your doctor determines the extent of the cancer based on the size of the tumor and whether the cancer has spread and, if so, how far.

Endometrial cancer is often staged based on the surgical removal of the tumor. To establish whether the cancer cells have spread, the surgeon may also remove nearby lymph nodes, tissues and fluid within the pelvic and/or abdominal cavity. A pathologist’s examination of these samples and information from imaging tests help the doctor determine an accurate and exact stage, which is the most important factor in choosing an appropriate treatment option.

Like many other cancer types, endometrial cancer is classified according to the tumor, node, metastasis (TNM) system developed by the American Joint Committee on Cancer (AJCC). The tumor (T) is analyzed and categorized based on its size and location, whether cancer cells occupy nearby lymph nodes (N), and whether cancer cells have metastasized (M) or spread to other organs and body parts. Once an endometrial cancer has been classified with this system, an overall stage is assigned (see Staging Illustrations).

Table 1. TNM Uterine Cancer Classifications

Classification Definition
Tumor (T)
Tis Carcinoma in situ (cancer is found only in the surface layer of cells lining the uterus and has not spread to deeper tissues of the uterus).
Tumor is found only in the body of the uterus (the corpus uteri).
Tumor is in the endometrium and may have spread to less than halfway through the myometrium.
Tumor has spread more than halfway through the myometrium; tumor has not spread beyond the body of the uterus.
Tumor has spread from the body of the uterus to the connective tissue of the cervix (cervical stroma) but has not spread outside of the uterus.
Tumor has spread outside the uterus but has not spread to the inner lining of the rectum or urinary bladder.
Tumor has spread to the outer surface of the uterus (the serosa) and/or to the tissue of the fallopian tubes or ovaries.
Tumor has spread to the vagina or to the tissues around the uterus.
T4 Tumor has spread to the inner lining (mucosa) of the rectum or the urinary bladder.
Node (N)
Nx Nearby lymph nodes cannot be evaluated.
N0 Cancer has not spread to nearby lymph nodes in the pelvis.
N1 Cancer has spread to nearby lymph node(s).
N2 Cancer has spread to lymph nodes along the aorta (para-aortic lymph nodes), which are located in the middle and upper portions of the abdomen; there may or may not be cancer in the nearby lymph nodes.
Metastasis (M)
M0 No distant metastasis
M1 Distant metastasis

Table 2. Stages of Uterine Cancer

Stage TNM Classification
0 (carcinoma in situ) Tis, N0, M0
T1, N0, M0
T1a, N0, M0
T1b, N0, M0
II T2, N0, M0
T3, N0, M0
T3a, N0, M0
T3b, N0, M0
T1 to T3, N1, M0
T1 to T3, N2, M0
IVA T4, any N, M0
IVB Any T, any N, M1




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