Stages, Grades and Types
Stages & Grades
Once uterine cancer is diagnosed, doctors will evaluate the size of the tumor and how far it has spread from where it originated. This classification, or staging, is a significant factor in determining the best treatment approach and predicting how successful it will be.
There are two systems used to stage uterine cancer – the FIGO (International Federation of Gynecology and Obstetrics) system and the AJCC (American Joint Committee on Cancer) TNM (tumor, node, metastasis) system. Both systems use basically the same information to stage uterine cancer:
- The size of the tumor and how deeply it goes into the muscle wall of the uterus.
- Whether the cancer has spread to any nearby lymph nodes.
- Whether the cancer has spread to distant lymph nodes or other parts of the body (metastasized).
There are 4 main stages of endometrial cancer and uterine sarcoma. Early diagnosis is typically, but not always, associated with better outcomes.
Cancer is usually staged twice. The first rating is called the clinical (baseline stage), based on tissue and images obtained before treatment. The second rating is done after treatment, such as surgery, and is called the pathologic stage.
Endometrial Cancer Stages
There are four main stages of cancer in the FIGO staging system: I, II, III, and IV. All stages, except for stage II, include subcategories with letters and sometimes numbers (eg, IIIB, IIIC2).
STAGE I: Cancer is in the uterus only. Stage I is divided into A and B depending on how far the cancer extends:
- IA: Cancer is either only in the endometrium or has invaded less than 50% of the thickness of the uterine muscle layer (myometrium).
- IB: Cancer has spread halfway or more into the myometrium.
STAGE II: Cancer has spread into the connective tissue of the cervix, but not outside the uterus.
STAGE III: Cancer has spread beyond the uterus and cervix, but not beyond the pelvis. Stage III is subclassified as A, B, or C depending on how far the cancer has spread within the pelvis:
- IIIA: Cancer has spread to the outer layer of the uterus and/or the fallopian tubes or ovaries.
- IIIB: Cancer has spread to the vagina or other tissues around the uterus (parametrium).
- IIIC1: Cancer has spread to nearby lymph nodes in the pelvis.
- IIIC2: Cancer has spread to farther lymph nodes near the aorta at the bottom of the spine.
STAGE IV: Cancer has spread beyond the pelvis to the bladder, the bowel, or other organs (metastasis). The degree of spread defines the A and B subcategories:
- IVA: Cancer has spread to the inner lining of the bladder and/or bowel.
- IVB: Cancer has spread to distant organs, such as the bones, lungs, pancreas, stomach, intestines, liver, or gallbladder.
Endometrial Cancer Grades
Endometrial cancer can also be described by its grade (G). The grade describes how abnormal the cells look and act under a microscope when compared with healthy cells. The difference is described as differentiation. Lower grade tumors are typically less aggressive and have a better outcome with treatment.
Grade X means that the grade cannot be evaluated.
Grade 1: The cancer tissue contains many healthy-looking cells and is called “well-differentiated.”
Grade 2: The cancer tissue contains more abnormal cells than healthy ones and is called “moderately differentiated.”
Grade 3: The cancer tissue has abnormal structure as well as a greater proportion of abnormal cells. These tumors are described as “poorly differentiated” or “undifferentiated.”
Uterine Sarcoma Stages
There are four main stages of uterine sarcoma in the FIGO staging system: I, II, III, and IV. All have subcategories defined by letters (eg, stage IIIA).
STAGE I: The tumor is small and only in the uterus. Stage I is divided into A and B according to tumor size:
- IA: Tumor is 5 cm across (about 2 inches) or smaller.
- IB: Tumor is larger than 5 centimeters (about 2 inches) across.
STAGE II: Cancer has spread beyond the uterus but remains in the pelvis. Stage II is subclassified as A or B depending on how far the cancer has spread within the pelvis:
- IIA: Cancer extends to the ovaries or fallopian tubes.
- IIB: Cancer has spread to other tissues in the pelvis.
STAGE III: Cancer is growing into tissues of the abdomen or farther but has not spread to distant sites. Stage III is divided into A, B, or C depending on the degree of spread:
- IIIA: Cancer has spread into abdominal tissues in 1 place only.
- IIIB: Cancer is growing into abdominal tissues in 2 or more places
- IIIC: Cancer has spread to nearby lymph nodes.
STAGE IV: There is cancer in the bladder or rectum, and possibly distant sites. The degree of spread defines the A and B subcategories:
- IVA: Cancer has spread to the bladder or rectum, but not distant sites.
- IVB: Cancer has spread to distant sites, such as the lungs, bones, or liver.
Uterine Cancer: Histologic Subtypes
Uterine cancers can be categorized into different subtypes based on key characteristics of individual cells under the microscope (histology).
Endometrial cancer originates in the endometrium, or inner lining of the uterus. The most common cancer cell type is endometrioid (80%). Certain less-common cell types are considered high-risk because they tend to grow more rapidly and are harder to treat. These include serous carcinoma, clear cell carcinoma, carcinosarcoma (also known as malignant mixed Müllerian tumor [MMMT]), and undifferentiated/dedifferentiated carcinoma.
Uterine sarcoma starts in the supporting tissues or muscles of the uterus. Cancer cell types include uterine leiomyosarcoma (uLMS), endometrial stromal sarcoma (ESS), and undifferentiated uterine sarcoma (UUS).