Staging skin cancer is crucial for determining the extent of the disease and guiding treatment decisions. While basal cell carcinomas typically do not spread and may not require staging, squamous cell carcinomas, although rare, can potentially metastasize and thus may require staging.
For melanoma, staging is primarily based on Breslow’s thickness of the tumor and whether it has spread to lymph nodes or other parts of the body. The staging system commonly used for all cancers is the TNM system:
- T indicates the size and depth of the tumor.
- N shows whether the cancer has spread to lymph nodes.
- M indicates whether the cancer has metastasized to another part of the body.
Based on these factors, skin cancer is categorized into stages ranging from 0 to 4. The lower the stage, the earlier the cancer is diagnosed. Most squamous cell skin cancers are diagnosed at stages 1 or 2.
For clinical stages I and II, tumors are categorized based on thickness and presence of ulceration:
- Stage Tis: Non-invasive tumor confined to the epidermis.
- Stage T1a/b: Invasive tumor less than or equal to 1.0 mm thick, with or without ulceration.
- Stage T2a/b: Tumor 1.01-2.0 mm thick, with or without ulceration.
- Stage T3a/b: Tumor 2.01-4.0 mm thick, with or without ulceration.
- Stage T4a/b: Tumor thicker than 4.0 mm, with or without ulceration.
Later clinical stage III is assigned if the cancer has metastasized beyond the original site, typically determined by examining nearby lymph nodes. The extent of metastasis determines the severity of stage III, considering factors such as the number of affected nodes and the presence of micrometastases.
Overall, staging provides valuable information for determining the appropriate course of treatment and assessing the prognosis of skin cancer.
When melanoma metastasizes, it commonly spreads to lymph nodes distant from the primary tumor or to internal organs. The most frequently affected organ is the lung, followed by the liver, brain, bone, and gastrointestinal tract in descending order of frequency. This spread of cancer to distant sites is a significant concern and may impact treatment decisions and prognosis. Early detection and appropriate management are crucial in addressing metastatic melanoma and improving patient outcomes.