How is melanoma skin cancer staged?

Skin cancer (melanoma) is staged using the TNM system:

T stands for tumor size and thickness. It's ranked from 0-4, with 0 being normal skin and 4 being the largest tumor size possible.

N stands for nodes, or lymph nodes, which are small glands throughout the body. Nodes are tested to see if they contain cancer cells. They are ranked from 0 to 3 with zero meaning that no cancer has spread to nearby nodes and three showing that there is extensive spread of melanoma to adjacent lymph nodes or other organs.

M stands for metastasis or whether it has spread beyond its original location. The levels range in severity from 0 (no metastasis present) to 1 (metastases present).

Once all these three parameters have been assessed, doctors can assign a stage based on those scores—stage I is considered low risk while stages III and IV indicate more advanced disease which requires more aggressive treatment options. Knowing what stage your melanoma is at will give you an idea of how severe your case is and help you plan out further steps accordingly.