Endometrial Cancer Stages

After being diagnosed with endometrial cancer, doctors will try to figure out if it has spread and, if so, how far. This process is called staging. The stage of a cancer describes how much and where cancer is in the body. Knowing how advanced the cancer is helps determine how best to treat it. The stage is one of the most important factors in deciding how to treat the cancer and determining how successful the treatment might be.

Doctors use diagnostic tests to determine the cancer's stage. They will need information based on samples of tissue collected during surgery. Because of this, staging may not be complete until all of the tests are finished and the surgery to remove the tumor has been done.

Endometrial cancer stages range from stage I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread to other parts of the body. And within a stage, an earlier letter means a lower stage. Although each person’s cancer is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

How is the endometrial cancer stage determined?

The 2 systems used for staging endometrial cancer are the FIGO (International Federation of Gynecology and Obstetrics) system and the American Joint Committee on Cancer TNM staging system.

They both stage (classify) this cancer based on 3 factors:

• The extent (size) of the tumor (T): How far has the cancer grown into the uterus? Has the cancer reached nearby structures or organs?
• The spread to nearby lymph nodes (N): Has the cancer spread to the para-aortic lymph nodes? These are the lymph nodes in the pelvis or around the aorta (the main artery that runs from the heart down the back of the abdomen and pelvis).
• The spread (metastasis) to distant sites (M): Has the cancer spread to lymph nodes or organs in other parts of the body?

Numbers or letters after T, N, and M give more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage.

The staging system in the table below uses the pathologic stage. It's determined by examining tissue removed during an operation. This is also known as surgical staging. Sometimes, if surgery isn't possible right away, the cancer will be given a clinical stage instead. The clinical stage is based on the results of a physical exam, biopsy, and imaging tests done before surgery. For more details, see Cancer Staging.

The FIGO staging system was updated in 2023 to reflect that some types of endometrial cancer are more aggressive than others.

Endometrial cancer staging can be complex, so ask your doctor to explain it to you in a way you understand.

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Stage	Stage grouping	FIGO Stage	Stage description*
I	T1 N0 M0	I	The tumor is growing inside the uterus and/or is limited to the uterus and ovary for non-aggressive types. The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).
IA	T1a N0 M0	IA	The tumor is limited to the endometrium (inner lining of the uterus) [IA1]. Or The tumor is a non-aggressive histologic type with growth less than halfway through the underlying muscle layer of the uterus (the myometrium) with no or focal lymphovascular space involvement (LVSI)** [IA2].  Or The tumor is a non-aggressive histologic type limited to the uterus and ovary [IA3]. The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).
IB	T1b N0 M0	IB	Non-aggressive histologic types with growth more than halfway through the myometrium, but not beyond the body of the uterus with no or focal LVSI [IB]     . The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).
IC		IC	Aggressive histologic types limited to the endometrium.
II	T2 N0 M0	II	The cancer has spread from the body of the uterus and is growing into the supporting connective tissue of the cervix (called the cervical stroma). Or There is substantial LVSI. Or The cancer is an aggressive histologic type with any invasion into the myometrium. The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).
IIA		IIA	Non-aggressive histologic type with invasion of the cervical stroma
IIB		IIB	Non-aggressive histologic type with substantial LVSI
IIC	T2 N0 M0	IIC	Aggressive histologic type with any myometrial invasion
III	T3 N0 M0	III	The cancer has spread outside the uterus, but has not spread to the inner lining of the rectum or urinary bladder (T3).
IIIA	T3a N0 M0	IIIA	The tumor has spread to the ovary or fallopian tube (and criteria for stage IA3 is not met) [IIIA1]   The tumor has spread to the outer surface of the uterus (called the serosa) [IIIA2].     The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).
IIIB	T3b N0 M0	IIIB	The cancer has spread to the vagina or to the tissues around the uterus (the parametrium). [IIIB1]            The cancer has spread to the pelvic peritoneum (The peritoneum is a sheet of smooth tissue that lines the abdomen and pelvis).[IIIB2] It has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).
IIIC1	T1-T3 N1, N1mi or N1a M0	IIIC1	The cancer has spread to pelvic lymph nodes (N1, N1mi, or N1a), but not to lymph nodes around the aorta or distant parts of the body (M0). IIIC1i Micrometastasis+ IIIC1ii Macrometastasis^
IIIC2	T1-T3 N2, N2mi or N2a M0	IIIC2	The cancer has spread to lymph nodes around the aorta (para-aortic lymph nodes) (N2, N2mi, or N2a), but not to distant parts of the body (M0).     IIIC2i The cancer has spread but is very small. It is a micrometastasis. IIIC2ii The cancer has spread but is very small. It is a macrometastasis.
IVA	T4 Any N M0		The cancer has spread to the inner lining of the rectum or urinary bladder (called the mucosa) (T4). It may or may not have spread to nearby lymph nodes (Any N), but has not spread to distant parts of the body (M0).
IVB	Any T Any N M1	IVB	The cancer has spread to the abdominal peritoneum. The cancer can be any size (Any T) and it might or might not have spread to other lymph nodes (Any N).
IVC		IVC	The cancer has spread to distant parts of the body such as lungs, liver, brain or bone or has spread to lymph nodes outside of the abdomen or lymph nodes above the kidneys.

*The following additional categories are not listed on the table above:

• TX: Main tumor cannot be assessed due to lack of information.
• T0: No evidence of a primary tumor.
• NX: Regional lymph nodes cannot be assessed due to lack of information. 

A pathology report may also indicate isolated tumor cells (ITCs). This is noted when small amounts of tumor (<0.2mm and <200 cells) are found in the lymph nodes. The significance of this finding is unknown at this time, but it will be noted as pN0(i+).

^**Lymphovascular space involvement (LVSI) = tumor cells are found around or near blood vessels or the lymph system.

⁺Micrometastasis = 0.2-2mm and/or >200 cells.

^{^}Macrometastasis = larger than 2 mm.

Endometrial cancer grade  

Doctors can also describe this type of cancer by its grade (G). The grade describes how closely cancer cells look like healthy cells when seen with a microscope.

The doctor compares the cancerous tissue with healthy tissue. Healthy tissue usually has many different types of cells grouped together.

• If the cancer looks similar to healthy tissue and has different cell groupings, it is called a differentiated or low-grade tumor.
• If the cancerous tissue looks very different from healthy tissue, it is called a poorly differentiated or high-grade tumor.

The cancer’s grade may help the doctor predict how quickly the cancer will grow. In general, the slower the growth, the better the prognosis.

The letter "G" is used to define a grade for uterine cancer.

GX: The grade cannot be evaluated.

G1: The cells are well differentiated.

G2: The cells are moderately differentiated.

G3: The cells are poorly differentiated.