The stage of a cancer tells the doctor how far it has spread. This is important because treatment is often decided according to the stage of a cancer.
It is important for a doctor to know which stage has your skin cancer got to because it give him and idea of how far that cancer has spread and what course of treatment should be applied for it.
A number of tests are carried out by the doctor to stage your skin cancer. However, most basal cells rarely spread and don’t really need any staging. They are only depicted if they grow very big. Staging is most likely done to detect squamous cell skin cancers which though rarely, but are still likely to spread.
Breslow’s Thickness of Skin Cancer
The method used to stage melanoma is based mainly on the thickness of the tumour and whether cancer has spread to lymph nodes or other parts of the body.
In situ (non-invasive) melanoma remains confined to the epidermis.
• Thin tumours are less than 1.0 millimetre (mm) in Breslow’s depth.
• Intermediate tumours are 1.0-4.0 mm.
• Thick melanomas are greater than 4.0 mm.
The number system
Doctors use a staging system that is common to all cancers. It is called the TNM system.
- The T indicates the size and depth of the tumour
- The N shows whether the cancer has spread to the lymph nodes
- The M shows whether the cancer has spread to another part of the body (metastasis)
Once the TNM categories (types) have all been decided, the information is put together to give a number stage from 0 to 4. The lower the stage, the earlier the cancer has been diagnosed. Most squamous cell skin cancers are diagnosed at stage 1 or 2.
Clinical Stages I and II (T categories)
- Stage Tis- The tumour is in situ and remains non-invasive in the epidermis.
- Stage T1a- The tumour is invasive but less than or equal to 1.0 mm in Breslow’s thickness, without ulceration and with a mitotic rate of less than 1/mm2.
- Stage T1b- The tumour is less than or equal to 1 mm thick. It is ulcerated and/or the mitotic rate is equal to or greater than 1/mm2.
- Stage T2a- The tumour is 1.01-2.0 mm thick without ulceration.
- Stage T2b- The tumour is 1.01-2.0 mm thick with ulceration.
- Stage T3a- The melanoma is 2.01-4.0 mm thick without ulceration.
- Stage T3b- The melanoma is 2.01-4.0 mm thick with ulceration.
- Stage T4a- The tumour is thicker than 4.0 mm without ulceration
- Stage T4b- The tumour is thicker than 4.0 mm with ulceration.
Later Clinical Stage III (N Category)
A tumour is assigned to Stage III if it has metastasized or spread beyond the original tumour site. This can be determined by examining a biopsy of the node nearest the tumour, known as the sentinel node. Just how advanced the tumour is into Stage III depends on factors such as whether the metastases are in-transit or have reached the nodes, the number of metastatic nodes, the number of cancer cells found in them, and whether or not they are micrometastases or can be seen with the naked eye.
Stage IV (M Category)
The melanoma has metastasized to lymph nodes distant from the primary tumour or to internal organs, most often the lung, followed in descending order of frequency by the liver, brain, bone, and gastrointestinal tract.
Image Courtesy: Getty
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