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Staging is a process of finding out how
widespread a cancer is. Because basal cell cancer so rarely spreads to other
organs, it is seldom staged unless the cancer is very large. Squamous cell
cancers have a somewhat greater (although still quite small) risk of spreading,
so staging may be done, particularly in people who have a high risk of spread.
This includes people with transplants whose immune system is suppressed with
drugs and people infected with HIV, the virus that causes AIDS. A staging system
is a way to summarize how far a cancer has spread. This helps members of the
cancer care team to plan appropriate treatment and determine a patient's
prognosis (the outlook for survival).
The most common system used to describe the stage of nonmelanoma skin cancer
is the TNM system. T stands for tumor (its size and how far it has
spread within the skin and to nearby tissues). N stands for spread to lymph nodes
(small bean-shaped collections of immune system cells that help the body fight
infections and cancers). M is for metastasis (spread to distant organs).
To assign a stage, information about the tumor and whether it has spread to
lymph nodes and other organs in the body is combined, according to a process
called stage grouping. The stages are described using the number 0 and
Roman numerals from I to IV. In general, patients with lower stage cancers have
a better prognosis for a cure or long-term survival.
The possible values for T are:
TX: Primary tumor cannot be assessed
T0: No evidence of primary tumor
Tis: Carcinoma in situ
T1: The tumor is 2.0 cm (about 4/5 inch) or smaller
T2: Tumor is larger than 2.0 cm but smaller than 5.0 cm (2 inches)
T3: Tumor is larger than 5 cm
T4: Tumor of any size that invades deeply into muscle, cartilage, or bone
The possible values for N are:
NX: Regional lymph nodes cannot be assessed
N0: No regional lymph node metastasis
N1: Metastasis to nearby lymph nodes
The M values are:
MX: Presence of distant metastasis cannot be assessed
M0: No distant metastasis
M1: Distant metastasis is present
Stage 0: Tis, N0, M0: Squamous cell carcinoma in situ, also called
Bowen’s disease, is the earliest stage of squamous cell skin carcinoma. The
cancer involves only the epidermis and has not spread to the dermis. In
contrast, Stage II, III, and IV cancers always involve the epidermis and dermis.
Stage I: T1, N0, M0: The cancer is no larger than 2 centimeters (between
3/4 and 7/8 inch). It has not spread to lymph nodes or other organs.
Stage II: T2 or 3, N0, M0: The cancer is larger than 2 cm (centimeters)
but has not spread to lymph nodes or other organs.
Stage III: T4, N0, M0 or Any T, N1, M0: The cancer has spread to tissues
beneath the skin (such as muscle, bone, or cartilage) and/or it has spread to
regional (nearby) lymph nodes. In this stage, the cancer has not spread to other
organs such as the lungs or brain.
Stage IV: Any T, Any N, M1: The cancer can be any size and may or may not
have spread to local lymph nodes. It has spread to other organs such as the
lungs or brain.
Revised 4-04
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