TNM Staging

A staging system for all cancers including breast cancer is another tool for the doctors to differentiate the tumors and to choose the best treatment for them. Staging can be divided in:
-Clinical staging
when is based in the information gathered before surgery, so information gathered from physical examination, radiological examination or endoscopy.
Pathological staging when is based in the information gathered after the surgery from the  examination of  the tumor microscopically.

The pathological staging is considered to be more accurate because allows the doctor to get a firsthand impression of the extension of the breast cancer. To differentiate they are used as small letters “c” or “p” before the stage.

TNM staging is another system  for the classification of malignant tumors. It was developed by Pierre Denoix (France) between the years 1943 and 19521. Since then it has been changed different times. The present seventh edition of TNM Classification contains rules of classification and staging that correspond with those appearing in the seventh edition of the AJCC Cancer Staging Manual (2009) and have approval of all national TNM committees.It should remain unchanged until some major advances in diagnosis or treatment relevant to a particular site requires reconsideration of the current classification.

T stands for tumor– it gives information about the tumor size:

  • TX is used when the tumor can’t be found or can’t be measured
  • T0 is used when there is no evidence of the primary tumor
  • Tis means cancer “ in situ” like intraductal carcinoma or lobular carcinoma in-situ
  • T1, T2, T3, T4 these numbers are used differentiate cancer based on the size and it extension in the nearby tissue. The lower the number that follows the T letter the lower the tumor or the less spread in the nearby tissue of the breast.

N stands for lymph node involvement– it gives information if the tumor has reached nearby lymph nodes:

  • NX is used when no lymph nodes are found or can be measured
  • N0 is used when the nearby lymph nodes don’t contain cancer cells
  • N1, N2, N3 these numbers are used to differentiate the involvement of the lymph nodes. The lower the number, the lower the extension in the nearby lymph nodes.

M stands for metastasis– it gives information if the tumor has been found or not in other part of the body:

  • MX is used when distant metastasis cannot be assessed
  • M0 is used when there is no distant metastasis
  • M1 is used when metastasis are found in other parts of the body distant from the origin place.

Once the T, N, and M categories have been determined, this information is combined in a process called stage grouping. Is very important to properly stage the tumor because from it depends the therapy used and the outcome of the treatment. There are different techniques to diagnose and properly stage tumor but we are going to talk about them in other articles

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