Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis (chance of recovery). There are different stage descriptions for different types of cancer.
One tool that doctors use to describe the stage is the TNM system. This system judges three factors: the tumor itself, the lymph nodes around the tumor, and if the tumor has spread to other parts of the body. The results are combined to determine the stage of cancer for each person. There are five stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.
TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:
- How large is the primary tumor and where is it located? (Tumor, T)
- Has the tumor spread to the lymph nodes? (Node, N)
- Has the cancer metastasized to other parts of the body? (Metastasis, M)
Tumor. Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. Specific tumor stage information is listed below.
TX: The primary tumor cannot be evaluated.
T0: There is no tumor.
Tis: The tumor is carcinoma in situ, an early cancer on the surface of the skin that has not spread to nearby tissue.
T1: The tumor is only in the vulva, or the vulva and perineum (the area of skin between the anus and vagina), and is 2 centimeters (cm) or smaller.
T1a: The tumor is only in the vulva, or the vulva and perineum, is 2 cm or smaller, and has spread no more than 1 millimeter (mm) into nearby structures.
T1b: The tumor is only in the vulva, or the vulva and perineum, is 2 cm or smaller, and has spread more than 1 mm into nearby structures.
T2: The tumor is only in the vulva, or the vulva and perineum, and is larger than 2 cm.
T3: The tumor, of any size, has spread to the lower urethra and/or the vagina or anus.
T4: The tumor has spread to any of the following: upper urethra, bladder mucosa, rectal mucosa, or is attached to the pubic bone.
Node. The “N” in the TNM staging system stands for lymph nodes. Lymph nodes near the pelvis and groin are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes.
NX: The regional lymph nodes cannot be evaluated.
N0: Cancer has not spread to the lymph nodes.
N1: Cancer has spread to lymph nodes on the same side of the body as the tumor.
N2: Cancer has spread to lymph nodes on both sides of the body.
Distant metastasis. The “M” in the TNM system indicates whether the cancer has spread to other parts of the body.
MX: Distant metastasis cannot be evaluated.
M0: There is no distant metastasis.
M1: There is metastasis to other parts of the body.
Cancer stage grouping
Doctors assign the stage of the cancer by combining the T, N, and M classifications.
Stage 0: The cancer has not spread from where it started and is on the surface of the skin of the vulva only (Tis, N0, M0).
Stage I: The tumor is smaller than 2 cm and has not spread (T1, N0, M0).
Stage IA: The tumor is smaller than 2 cm, has not spread, and is no deeper than 1 mm (T1a, N0, M0).
Stage IB: The tumor is smaller than 2 cm, has not spread, and is deeper than 1mm (T1b, N0, M0).
State II: The tumor is larger than 2 cm, is in the vulva or perineum or both, but has not spread to nearby tissue (T2, N0, M0).
Stage III: The cancer has spread to nearby tissue (vagina, anus, urethra) and/or lymph nodes on one side of the body, but there is no distant metastasis (T1 or T2, N1, M0; T3, N0 or N1, M0).
Stage IVA: The cancer has spread to lymph nodes on both sides of the body or spread into the upper part of the urethra, bladder, rectum, or pelvic bone (T1, T2, T3; N2, M0; or T4, any N, M0).
Stage IVB: Any cancer that has spread to a distant part of the body (any T, any N, M1).
Recurrent: Recurrent cancer is cancer that comes back after treatment. If there is a recurrence, the cancer may need to be staged again (called re-staging) using the system above.
Tumor grade (G). In addition to the TNM system, doctors also describe a primary tumor by its grade, which is determined by using a microscope to examine tissue from a tumor. The doctor compares the tumor tissue with normal tissue. Healthy tissue contains many different types of cells grouped together, which is called differentiated. Tissue from a tumor usually has cells that look more alike, called poorly differentiated. Generally, the more differentiated the tissue, the better the prognosis.
GX: The tumor grade cannot be evaluated.
G1: The tumor cells are well differentiated (contain many healthy-looking cells).
G2: The tumor cells are moderately differentiated (more cells appear abnormal than healthy).
G3: The tumor cells are poorly differentiated (most of the cells appear abnormal).
G4: The tumor cells are undifferentiated (the cells barely resemble healthy cells).
Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Seventh Edition (2010) published by Springer-Verlag New York, www.cancerstaging.net.