In the context of pathology, staging refers to the evaluation of a disease in terms of its progression in the body, or 'stage.' This term is most often used in the context of oncology to establish the stage of development of a certain cancer. To stage a tumor, a pathologist examines tissue from the tumor or uses imaging techniques such as x-rays, CT Scans, Magnetic Resonance Imaging (MRI) scans, or other radiological scans such as a Gallium Scan. Once this information is compiled, physicians are able to determine how much the disease has progressed and the extent to which it may have spread to other parts of the body. This information is necessary to decide upon the best possible course of treatment. Staging applies to almost every cancer except for leukemia, as this cancer involves the blood and is not localized to one area of the body. Some classifications of leukemia have their own staging systems to reflect the disease's advancement.
Stage migration is the change of disease from one stage to another.
Systems of staging
Systems of staging may differ between diseases or specific manifestations of a disease. For example, staging of colon cancer originally consisted of four stages: A,B,C,and D, whereas staging of Hodgkin's Disease 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. More recently, colon cancer staging is indicated either by the original A-D stages or by the American Joint Committee on Cancer's TNM staging system, which uses stages I-IV.
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.
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 T2N1M0 cancer would be a cancer with a T1 tumor, N2 involvement of the lymph nodes, and no metasteses (no spreading through the body). Tumor 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.
See also
