Cancer staging

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Providing a correct description of the cancer is essential for selecting the best treatment and assessing the prognosis.

Staging refers to the study of the extent (size and location) and spread of the tumour (local or dispersed). Staging helps:

  • Assess the severity of the cancer and likelihood of complications.
  • Design the best possible treatment plan.
  • Make a prognosis.

Tumours are usually staged according to the TNM system:

  • T refers to the tumour diameter in centimetres and measures the size of the primary tumour and any invasion into neighbouring tissue.
  • N refers to the spread of the cancer to nearby lymph nodes (or glands).
  • M refers to whether the cancer has spread from the primary tumour to other parts of the body (metastasis).

Other ways of describing the stage

The following stages can be used to describe the type of cancer:

  • Stage 0. Abnormal cells are present, but they have not spread to nearby tissue. Also called carcinoma in situ or CIS. Carcinoma in situ or CIS is not cancer, but it may develop into cancer.
  • Stages I, II and III. Cancer has developed. The higher the number, the larger the tumour and the more it has spread to nearby tissues.
  • Stage IV. The cancer has spread to distant parts of the body.

This classification can be made with the same tests used in the diagnosis or may require specific complementary tests. The identification of tumour markers or the sentinel lymph node technique, as in the case of breast cancer, are examples of complementary studies beyond those used in the diagnosis.

The following terms are also used when describing cancer:

  • In situ. There are abnormal cells, but they have not spread to nearby tissues.
  • Localised. The cancer is limited to the point of origin, it has not spread.
  • Regional. The tumour has spread to nearby structures such as tissues, organs and/or lymph nodes.
  • Distant. The cancer has spread to distant parts of the body, known as metastasis.
  • Unknown staging. There is not enough information to define the stage of the tumour.

Substantiated information by:

Albert Tuca Rodríguez
Aleix Prat
Francesc Balaguer
Meritxell Molla
Montserrat Valverde Bosch
Vanessa Vilas
Álvaro Urbano-Ispizua

Published: 12 November 2018
Updated: 20 November 2018

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