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Grading and staging are ways of describing how fast-growing the cancer is and how much it has grown, including where the cancer is located and if or where it has spread. Doctors use diagnostic tests to determine the cancer's grade and stage, so grading and staging may not be complete until all the tests are finished. Knowing the grade and stage helps the doctor to decide what kind of treatment is best and helps predict a patient's prognosis (chance of recovery).
Histologic grade describes how much the cancer cells look like normal tissue under a microscope. A tumor's grade is described using the letter “G” and a number. Grade is important because it helps to predict the likelihood that the cancer has spread. 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 (called well differentiated).
G2: The cells are somewhat different from normal cells (called moderately differentiated).
G3: Describes tumor cells that look very much like each other, but don’t look very much like normal cells (called poorly differentiated).
G4: The tumor cells barely look like normal cells (called undifferentiated).
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, lymph nodes around the tumor, and if the tumor has spread to the rest of the body. The results are combined to determine the stage of cancer for each person. There are five stages of penile cancer: 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, where is it located and what is the grade of the tumor (see Grading above)? (Tumor, T)
- Has the tumor spread to the lymph nodes near the tumor? (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 and/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 patient. Specific tumor stage information is listed below:
TX: The primary tumor cannot be evaluated.
T0: There is no tumor.
Tis: An early cancer that has not spread to other tissue. This is also called carcinoma in situ.
Ta: The tumor is a noninvasive, verrucous (wart-like) carcinoma, which looks somewhat like a small piece of broccoli or cabbage.
T1a: The tumor has grown into the subepithelial connective tissue (tissue below the top layers of skin). The tumor has not grown into blood or lymph vessels, and the tumor grade (see above) is G2 or lower.
T1b: The tumor has grown into the subepithelial connective tissue. The tumor has grown into blood or lymph vessels, and/or the tumor grading is G3 or higher.
T2: The tumor has grown into the corpus spongiosum or corpora cavernosum (internal chambers of the penis).
T3: The tumor has grown into the urethra.
T4: The tumor has grown into other nearby structures.
Node. The “N” in the TNM staging system stands for lymph nodes near the cancer (called regional lymph nodes). The regional lymph nodes for penile cancer are located in the groin and the pelvis. Lymph nodes in other parts of the body are called distant lymph nodes. Staging places cancers that have spread to regional lymph nodes and cancers that have spread to distant lymph nodes in separate categories. The N in TNM staging only refers to the regional lymph nodes.
If the doctor evaluates the lymph nodes before the biopsy or surgery, based on a physical examination and/or other tests, the letter “c” (for “clinical” staging) is placed in front of the N. If the doctor evaluates the lymph nodes after a biopsy or surgical removal of the lymph nodes, which is more accurate, the letter “p” (for “pathologic” staging) is placed in front of the N. The information below describes the pathologic staging.
pNX: The regional lymph nodes cannot be evaluated.
pN0: Cancer has not spread to the regional lymph nodes.
pN1: Cancer has spread to a single inguinal lymph node (lymph node in the groin).
pN2: Cancer has spread to more than one inguinal lymph node on the same side or both sides of the body.
pN3: The cancer has spread to one or more inguinal (groin) lymph nodes, and it has grown from that lymph node into the surrounding tissue in the groin, and/or the cancer has spread beyond the lymph nodes in the groin or pelvis, on the same side or both sides of the body.
Distant metastasis. The “M” in the TNM system indicates whether the cancer has spread from the penis to other parts of the body.
MX: Distant metastasis cannot be evaluated.
M0: There is no distant metastasis.
M1: There is metastasis to parts of the body other than the penis and the regional lymph nodes.
Cancer stage grouping
Doctors assign the stage of the cancer by combining the T, N, and M classifications.
Stage 0: The cancer has not grown below the superficial (surface) layer of skin, and it has not spread to lymph nodes or distant parts of the body (Tis or Ta; N0, M0).
Stage I: A low-grade cancer has grown just below the superficial layer of skin. It has not spread to lymph nodes or distant parts of the body (T1a, N0, M0).
Stage II: The cancer is invasive and is high grade and/or has grown into blood or lymph vessels and/or into the internal chambers of the penis and/or the urethra. There is no spread to lymph nodes or distant parts of the body (T1b, T2, or T3; N0, M0).
Stage IIIa: The cancer has grown no further than the urethra, and has spread to a single groin lymph node, but has not spread to distant parts of the body (T1, T2, or T3; N1, M0).
Stage IIIb: The cancer has grown no further than the urethra, and has spread to more than one groin lymph node, but it has not spread to pelvic lymph nodes or distant parts of the body (T1, T2, or T3; N2, M0).
Stage IV: Any of the following:
- The cancer has grown into nearby tissues (T4, any N, any M).
- The cancer has spread to one or more inguinal (groin) lymph nodes, and it has grown from that lymph node into the surrounding tissue in the groin (any T, N3, any M).
- The cancer has spread to at least one lymph node in the pelvis (any T, N3, any M) and/or to distant lymph nodes outside the pelvis or to other parts 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.
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.