Melanoma in situ (stage 0)
Melanoma in situ is also called stage 0 melanoma.
It means there are cancer cells in the top layer of skin (the epidermis). The melanoma cells are all contained in the area in which they started to develop and have not grown into deeper layers of the skin.
Some doctors call in situ cancers pre cancer. In a way, they are. Although the cells are cancerous, they cannot spread to other parts of the body, so in situ cancers are not a cancer in the true sense. But if they are not treated, in situ cancers can develop into invasive cancer.
TNM stages
TNM stands for Tumour (T), Node (N) and Metastasis (M). The staging is different depending on the type of cancer you have.
The information below is an overview of the TNM staging for all types of cancer.
- T describes the size of the tumour (cancer)
- N describes whether there are any cancer cells in the nearby lymph nodes
- M describes whether the cancer has spread to parts of the body further away from where the cancer started
The doctor gives each factor (T, N and M) a number. The number depends on how far the cancer has grown or spread.
So, a very small cancer which hasn't spread to the lymph nodes or elsewhere in the body may be T1 N0 M0.
A larger cancer that has spread into the nearby lymph nodes and to another part of the body may be T3 N1 M1.
In the TNM staging system melanoma in situ is the same as Tis, N0, M0.
Treatment
The stage of your cancer helps your doctor to decide what treatment you need. Treatment also depends on:
- where the melanoma is
- your general health and level of fitness
Surgery is the main treatment. To diagnose melanoma doctors remove the abnormal area of skin and a small area of surrounding skin. You may then need a second operation to remove a larger area of healthy tissue around where the melanoma was. This is called a wide local excision. As long as the doctors are sure they removed enough tissue, this is all the treatment you need.
Surgery can cause scarring and some people may not be well enough to have an operation. Instead of surgery, you might have treatment with a cream called imiquimod. You put imiquimod on the affected area, over a period of weeks.
Or your doctor might suggest having regular ultrasound scans of the lymph nodes to check if the cancer grows (progresses). This is called surveillance.