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 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 (spread) 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. This helps the doctor develop the best treatment plan for each individual. 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 (early-stage cancer that has not spread to nearby tissue).
T1: The tumor is limited to the fallopian tube(s).
T1a: The tumor is contained within one fallopian tube. No part of the tumor has spread to the surface of the tube, and no cancer cells are found in abdominal fluid.
T1b: An encapsulated (self-contained) tumor is in both fallopian tubes, but neither tumor is touching a tube surface. No cancer cells are found in abdominal fluid.
T1c: The tumor is in one or both fallopian tubes, but the capsule has ruptured (burst) or the tumor has spread to the tube surface, or cancer cells are found in the abdominal fluid.
T2: The tumor involves one or both fallopian tubes and has spread to the pelvis.
T2a: Tumor extensions (areas of tumor growth also called implants) are found on the uterus and/or ovaries but no cancer cells are found in the abdominal fluid.
T2b: There is cancer in other pelvic tissue, but no cancer cells are found in the abdominal fluid.
T2c: Tumor extensions in the pelvis are present, such as in T2a or T2b, but cancer cells are also in the abdominal fluid.
T3: The tumor involves one or both fallopian tubes and has spread microscopically into the abdominal area outside the pelvis.
T3a: Microscopic metastasis is present in the peritoneal area (the area around the organs in the abdomen) beyond the pelvis.
T3b: Metastasis measuring 2 centimeters (cm; a little smaller than 1 inch) or smaller is present outside the pelvis.
T3c: Metastasis larger than 2 cm is present in areas outside the pelvis.
Nodes. The “N” in the TNM staging system stands for lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes near the pelvis 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: There is no cancer in the regional lymph nodes.
N1: The cancer has spread to the pelvic lymph nodes.
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 cancer beyond the peritoneal area.
M1: The cancer has spread beyond the peritoneal area.
Cancer stage grouping
Doctors assign the stage of the cancer by combining the T, N, and M classifications.
Stage 0: Refers to carcinoma in situ (Tis, N0, M0).
Stage I: Cancer is located only in the fallopian tubes (T1, N0, M0).
Stage IA: An encapsulated tumor is located in only one fallopian tube, with no spread to pelvic lymph nodes or other parts of the body (T1a, N0, M0).
Stage IB: An encapsulated tumor is in both fallopian tubes, with no spread to pelvic nodes or other parts of the body (T1b, N0, M0).
Stage IC: Cancer is in one or both fallopian tubes with either a ruptured capsule or tumor spread to the ovarian surface, or cancer cells are in the abdominal fluid (T1c, N0, M0).
Stage II: Cancer is in one or both fallopian tubes and has grown into the pelvis but not elsewhere (T2, N0, M0).
Stage IIA: Cancer has spread to the uterus or ovaries, but not to the pelvic lymph nodes or distant organs (T2a, N0, M0).
Stage IIB: Cancer has spread to other pelvic tissue, but not to lymph nodes or distant organs (T2b, N0, M0).
Stage IIC: Cancer has spread into the pelvic area and is shedding cancer cells into abdominal fluid (T2c, N0, M0).
Stage III: Cancer is in one or both fallopian tubes and the pelvis and has spread into the peritoneum but not to distant parts of the body (T3, N0, M0).
Stage IIIA: Cancer has spread microscopically throughout the pelvis (T3a, N0, M0).
Stage IIIB: Cancer has spread into the peritoneal area with implants that are 2 cm or smaller (T3b, N0, M0).
Stage IIIC: Describes any cancer that has spread into the peritoneal area in implants larger than 2 cm (T3c, N0, M0), or the tumor has spread to lymph nodes and/or the pelvis, but not to other parts of the body (any T, N1, M0).
Stage IV: Describes any cancer that has spread to distant organs (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.
Histologic grade (G). Doctors may also assign a grade to the disease. A tumor’s grade uses the letter “G” and a number, and describes how closely the cancer cells resemble normal tissue under a microscope. Cells that look like healthy cells are low grade, and those that look like cancer cells are high grade. In general, the lower the grade, the better the prognosis.
GX: The tumor grade cannot be identified.
G1: Describes cells that look more like normal tissue cells (well differentiated).
G2: The cells are somewhat different (moderately differentiated).
G3: The tumor cells barely resemble normal cells (poorly differentiated).
G4: The cells do not look like normal cells (undifferentiated).
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 .