<unk>  is the assessment of the extent to which a<unk><unk>  has spread from its original source. As with most<unk> s,<unk>  is an important determinant of treatment and prognosis. In general, more advanced stages of<unk>  are less amenable to treatment and have a worse prognosis. The initial evaluation of non-small cell<unk>  uses the TNM classification. This is based on the size of the primary tumor, lymph node involvement, and distant metastasis. After this, using the TNM descriptors, a group is assigned, ranging from occult<unk> , through stage 0, IA (one-A), IB, IIA, IIB, IIIA, IIIB to IV (four). This stage group assists with the choice of treatment and estimate of prognosis. There are several methods by which this assessment is made. They are broadly classified into non-invasive techniques, which generally involve medical imaging of the<unk> s such as computer tomography (CT) scans and PET scans, and invasive techniques such as biopsy and surgery. Invasive techniques provide additional information because tissue samples can be seen microscopically to confirm presence of<unk>  cells (as opposed to enlargement of tissues due to other causes such as infection) and to determine the type of<unk><unk>  and its grade.<unk>  may also be categorized as either clinical or as pathological/surgical<unk> . Clinical<unk>  is performed prior to definitive surgery. It is based on the results of imaging studies (such as CT scans ) and biopsy results (i.e. clinical<unk>  does include the results of biopsy, an "invasive technique.") Pathological<unk>  is also called surgical<unk>  and reflects not only the results of non-surgical biopsy, but is evaluated either intra- or post-operatively and is based on the combined results of surgical and clinical findings, including surgical sampling of thoracic lymph nodes.
Lung cancer staging
Prostate cancer staging
Cancer staging
Colon cancer staging
Response evaluation criteria in solid tumors
PET response criteria in solid tumors
Breast cancer management
Tuberculosis management