Cancer staging: Encyclopedia - Cancer staging

Cancer staging

The stage of a cancer is a descriptor (usually numbers I to IV) of how much the cancer has spread. The stage often takes into account the size of a tumor, how deep it has penetrated, whether it has invaded adjacent organs, if and how many lymph nodes it has metastasized to, and whether it has spread to distant organs. Staging of cancer is important because the stage at diagnosis is the biggest predictor of survival, and treatments are often changed based on the stage.

Cancer staging - Clinical staging and pathological staging

Cancer staging can be divided into a clinical stage and a pathologic stage. In the TNM (Tumor, Node, Metastasis) sytem, clinical stage and pathologic stage are denoted by a small 'c' or 'p' before the stage, e.g. cT3N1M0 or pT2N0.

• Clinical stage is based on all of the available information obtained before a surgery to remove the tumor. Thus, it may include information about the tumor obtained by physical examination, radiologic examination, and endoscopy.
• Pathologic stage adds additional information gained by examination of the tumor microscopically by a pathologist.

Because they use different information, clinical stage and pathologic stage are often different. Pathologic staging is usually considered the "better" or "truer" stage because it allows direct examination of the tumor and its spread, contrasted with clinical staging which is limited by the fact that the information is obtained by making indirect observations at a tumor which is still in the body. However, clinical staging and pathologic staging should complement each other. Not every tumor is treated surgically, so sometimes pathologic staging is not available. Also, sometimes surgery is preceded by other treatments such as chemotherapy and radiation therapy which shrink the tumor, so the pathologic stage may underestimate the true stage.

Cancer staging - Systems of staging

Staging systems are specific for each type of cancer (e.g. breast cancer and lung cancer). Some cancers, however, don't have a staging system. Often competing staging sytems exist for the same type of cancer; however, the universally-accepted staging system is that of the UICC, which has merged its staging system with that of the AJCC.

Cancer staging - Blood

• lymphomas: uses Ann Arbor staging

• Hodgkin's Disease#Staging: follows a scale from I-IV and can be indicated further by an A or B, depending on whether a patient is unsymptomatic or has symptoms such as fevers. It is known as the "Cotswold System" or "Modified Ann Arbor Staging System". [1]

Cancer staging - Solid

For solid tumors, TNM is by far the most commonly used system, but it has been adapted for some conditions.

• breast_cancer#Staging: Uses TNM [2]

• cervical cancer#Staging: uses "FIGO" (similar to TNM). For premalignant dysplastic changes, the CIN (cervical intraepithelial neoplasia) grading system is used. [3]

• colon_cancer#Staging: originally consisted of four stages: A,B,C,and D (the "Duke Staging System"). More recently, colon cancer staging is indicated either by the original A-D stages or by TNM. [4]

• kidney cancer: uses TNM [5]

• cancer of the larynx: Uses TNM [6]

• liver cancer#Staging_and_prognosis: uses Stages I-IV [7]

• lung cancer: uses TNM [8] or [9]

• malignant_melanoma#Staging: TNM used. Also of importance are the "Clark level" and "Breslow depth" which refer to the microscopic depth of tumor invasion ("Microstaging"). [10]

• prostate cancer staging: outside of US, TNM almost universally used. Inside US, Jewett-Whitmore somtimes used. [11].

• skin cancer: uses TNM [12]

Cancer staging - Overall stage grouping

Overall Stage Grouping is also referred to as Roman Numeral Staging. This system uses numerals I,II,III, and IV to describe the progression of cancer.

• Stage I cancers are localized to one part of the body.
• Stage II cancers are locally advanced, as are Stage III cancers. Whether a cancer is designated as Stage II or Stage III can depend on the specific type of cancer; for example, in Hodgkin's Disease, Stage II indicates affected lymph nodes on only one side of the diaphragm, whereas Stage III indicates affected lymph nodes above and below the diaphragm. The specific criteria for Stages II and III therefore differ according to diagnosis.
• Stage IV cancers have often metastisized, or spread to other organs or througout the body.

Within the OSG system, a cancer may also be designated as recurrent, meaning that it has appeared again after being in remission or after all visible tumor has been eliminated. Recurrence can either be local, meaning that it appears in the same location as the original, or distant, meaning that it appears in a different part of the body.

Cancer staging - TNM staging

TNM Staging is used for solid tumors, and is an acronym for the words Tumor, Nodes, and Metastases. Each of these criteria is separately listed and paired with a number to indivate the TNM stage. A T1N2M0 cancer would be a cancer with a T1 tumor, N2 involvement of the lymph nodes, and no metastases (no spreading through the body).

• Tumor (T) refers to the primary tumor and carries a number of 0 to 4.
• N represents regional lymph node involvement and can also be ranked from 0 to 4.
• Mestastasis is represented by the letter M, and is 0 if no metastasis has occurred or 1 if metastases are present.

Cancer staging - Stage migration

Stage migration is the artificial change in the stage of a cancer produced by either a change in the staging system itself or a change in technology which allows more sensitive detection of tumor spread (e.g. the use of MRI scan). Stage migration can lead to curious statistical phenomena. See Will Rogers phenomenon.

Adapted from the Wikipedia article "Cancer staging", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki