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.

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) but not in the muscle tissue (myometrium) of the uterus.
• T1b (Stage IB). Tumor has spread to the myometrium but is in less than half of the myometrium.
• T1c (Stage IC). Tumor has spread to more than half of the myometrium.
• T2 (Stage II). Tumor has spread from the uterus to the cervix but has not spread outside the uterus.
• T2a (Stage IIA). Tumor has spread to the glandular cells in the endocervical canal but not into the connective tissue (stroma) of the cervix.
• T2b (Stage IIB). Tumor is in the connective tissue (stromal layer) of the cervix.
• T3 (Stage III). Tumor has spread outside of the uterus but not outside of the pelvis. It has not spread to the bladder or rectum. Lymph nodes in the pelvis may contain cancer cells.
  • Stage IIIB:
  • Stage IIIC: Tumor has spread to lymph nodes in the pelvis.
• T3a (Stage IIIA). Tumor is on the outer surface of the uterus, or in the ovaries or fallopian tubes, or is present in the peritoneal fluid in the pelvis and abdomen.
• 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 (IIIC). Cancer has spread to lymph nodes near the primary tumor.

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

• MX. Distant metastasis cannot be assessed.
• M0. No distant metastasis is found.
• M1 (IVB). Metastasis to another area of the body has occurred.

The TNM staging system allows your health professional 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.

Classification of endometrial cancer

FIGO stage	TNM class
Stage 0 Stage I Stage IA Stage IB Stage IC	Tis T1N0M0 T1aN0M0 T1bN0M0 T1cN0M0
Stage II Stage IIA Stage IIB	T2N0M0 T2aN0M0 T2bN0M0
Stage III Stage IIIA Stage IIIB Stage IIIC	T3N0M0 T3aN0M0 T3bN0M0 T1N1M0 T2N1M0 T3N1M0
Stage IVA Stage IVB	T4, any N, M0 Any T, any N, M1

Grade of endometrial cancer

The grade of endometrial cancer refers to how the cancer cells look under a microscope. 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 cancers have very clear boundaries and cells that look relatively normal. They normally do not grow and spread rapidly.
• G2: Moderately differentiated cancer has more abnormal looking cells and cell boundaries.
• G3: Poorly differentiated cancers have less clearly defined boundaries and cells that look very abnormal. They often grow and spread rapidly.

Citations

1. American Joint Committee on Cancer (2002). Corpus uteri. In AJCC Cancer Staging Manual, 6th ed., pp. 267–273. New York: Springer-Verlag.