Stage and Grade of Endometrial Cancer

Treatment for endometrial cancer depends on the size, stage, and grade of the cancer.

• The stage determines the extent of cancer growth in and beyond the uterus. Staging is done when the uterus is removed (hysterectomy). The surgeon will examine the other pelvic organs to look for signs of cancer and remove them if necessary.
• The grade of endometrial cancer refers to how the cancer cells look under a microscope. Learning the grade can help your doctor decide which treatments will work best for you.

Endometrial cancer has been classified by the American Joint Committee on Cancer (AJCC) and the Fédération Internationale de Gynécologie et d’Obstétrique (FIGO, also called the International Federation of Gynecology and Obstetrics). The two classification systems are very similar.¹

AJCC TNM and FIGO staging classification

The primary tumor (T) is staged in the following way with the AJCC classification first and the FIGO stage in parentheses:

• TX. Primary tumor cannot be assessed.
• T0. No primary tumor is seen.
• Tis (Carcinoma in situ). The cancer is found only in one area of the uterus and only in a few layers of cells.
• T1 (Stage I). Tumor is contained in the uterus. It has not spread to the cervix.
• T1a (Stage IA). Tumor is in the lining of the uterus (endometrium) or has spread into less than one-half of the muscle tissue (myometrium) of the uterus.
• T1b (Stage IB). Tumor has spread to one-half or more of the myometrium.
• T2 (Stage II). Tumor has spread from the uterus to the cervix but has not spread outside the uterus.
• T3a (Stage IIIA). Tumor is on the outer surface of the uterus, or in the ovaries or fallopian tubes.
• T3b (Stage IIIB). Tumor has spread (metastasized) into the tissue layers of the vagina.
• T4 (Stage IVA). Tumor has spread into the bladder or rectum.

After the tumor (T) is staged, the TNM system stages lymph node involvement (N) to help determine the treatment options at each stage. Lymph node involvement is staged in the following way:

• NX. Lymph nodes near the primary tumor cannot be evaluated.
• N0. Cancer has not spread to lymph nodes near the primary tumor.
• N1 (IIIC1). Cancer has spread to lymph nodes near the primary tumor.
• N2 (IIIC2). Cancer has spread to the lymph nodes near the aorta, with or without spreading to the pelvic lymph nodes.

The last part of staging endometrial cancer is to find out whether cancer has spread to other areas of the body (metastasized). The TNM system stages metastasis (M) in the following way:

• M0. No distant metastasis is found.
• M1 (IVB). Metastasis to another area of the body has occurred, but not to the vagina, to the pelvic membranes and adjoining tissue, or to the lymph nodes near the aorta.

The TNM staging system allows your doctor to recommend the most effective treatment options and discuss the long-term outcome (prognosis) based on the type of tumor, the stage of your cancer, your age and overall health condition.

The FIGO stages and the AJCC TNM class are grouped in the following table.

Grade of endometrial cancer

The grade of endometrial cancer refers to how the cancer cells look under a microscope. Knowing the grade can help your doctor decide which treatment options are best for you. Endometrial cancer cells are described as well-differentiated, moderately differentiated, or poorly differentiated. Differentiation is a term used to describe how clearly the cancer cells can be distinguished from the surrounding normal tissues and how normal or abnormal the cells look.

• GX. Grade cannot be assessed
• G1: Well-differentiated
• G2: Moderately differentiated
• G3–G4: Poorly differentiated or undifferentiated