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.
What are the letters and numbers that appear in my diagnosis?
When a cancer is classified according to the TNM system there is a series of numbers after each letter that provides further information about the cancer.
Primary tumour (T)
TX: Primary tumour cannot be measured.
T0: Primary tumour cannot be found.
T1, T2, T3, T4: Refers to the size and/or extent of the main tumour. The higher the number after the T, the larger the tumour or the more it has spread into nearby tissues. T stages can be further divided to offer even more detail, for example T3a or T3b.
Regional lymph nodes (N)
NX: No cancer can be detected in nearby lymph nodes.
N0: There is no cancer in nearby lymph nodes.
N1, N2, N3: Refers to the number and location of lymph nodes with cancer. The higher the number after the N, the more lymph nodes have cancer.
Distant metastasis (M)
MX: No metastasis can be measured.
M0: The cancer has not spread to other parts of the body.
M1: The cancer has spread to other parts of the body.
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.