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Cancer staging is the process of determining the extent to which a cancer has developed by spreading. Contemporary practice is to assign a number from I-IV to a cancer, with I being an isolated cancer and IV being a cancer which has spread to the limit of what the assessment measures. The stage generally takes into account the size of a tumor, whether it has invaded adjacent organs, how many regional (nearby) lymph nodes it has spread to (if any), and whether it has appeared in more distant locations (metastasized). ==TNM staging system== (詳細はTNM (Tumor, Node, Metastasis) system, clinical stage and pathologic stage are denoted by a small "c" or "p" before the stage (e.g., cT3N1M0 or pT2N0). This staging system is used for most forms of cancer, except brain tumors and hematological malignancies. * 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, blood tests, radiologic examination, biopsy, and endoscopy. * Pathologic stage adds additional information gained by examination of the tumor microscopically by a pathologist after it has been surgically removed. Because they use different criteria, clinical stage and pathologic stage often differ. Pathologic staging is usually considered to be more accurate because it allows direct examination of the tumor in it entirety, contrasted with clinical staging which is limited by the fact that the information is obtained by making indirect observations of a tumor which is still in the body. However, clinical staging and pathologic staging often complement each other. Not every tumor is treated surgically, therefore pathologic staging is not always 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cancer staging」の詳細全文を読む スポンサード リンク
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