Melanoma staging describes the extent of the cancer and helps determine the best treatment approach and prognosis. The staging system most commonly used is the American Joint Committee on Cancer (AJCC) TNM system, which considers Tumor size (T), lymph Node involvement (N), and Metastasis (M). Here is a detailed look at the stages of melanoma:

Stage 0 (Melanoma in Situ)

• Description: Melanoma cells are found only in the outermost layer of skin (the epidermis) and have not spread deeper.
• Implications: This is the earliest stage and is highly treatable with surgical removal.
• Sources: American Cancer Society, Mayo Clinic

Stage I

• Stage IA
  • Description: The tumor is up to 1 mm thick, with no ulceration. Melanoma has not spread to lymph nodes or distant sites.
• Stage IB
  • Description: The tumor is up to 1 mm thick with ulceration or 1-2 mm thick without ulceration. No spread to lymph nodes or distant sites.
• Implications: Early stage; treatment typically involves surgery to remove the tumor and a margin of healthy tissue.
• Sources: American Cancer Society, National Cancer Institute

Stage II

• Stage IIA
  • Description: The tumor is 1-2 mm thick with ulceration or 2-4 mm thick without ulceration.
• Stage IIB
  • Description: The tumor is 2-4 mm thick with ulceration or more than 4 mm thick without ulceration.
• Stage IIC
  • Description: The tumor is more than 4 mm thick with ulceration.
• Implications: Intermediate stage; treatment usually involves wide excision surgery and may include a sentinel lymph node biopsy.
• Sources: American Cancer Society, National Cancer Institute

Stage III

• Stage IIIA
  • Description: Melanoma has spread to one or more nearby lymph nodes, but the nodes are not enlarged (micrometastases). The primary tumor may be of any thickness, without ulceration.
• Stage IIIB
  • Description: Melanoma has spread to one or more nearby lymph nodes, which may be enlarged (macrometastases), or has in-transit metastases/satellites without ulceration.
• Stage IIIC
  • Description: Melanoma has spread to one or more lymph nodes with ulceration, or in-transit metastases/satellites with ulceration.
• Stage IIID
  • Description: Melanoma has spread to four or more lymph nodes with ulceration, or there are matted lymph nodes or in-transit metastases/satellites with ulceration.
• Implications: Advanced stage; treatment often involves surgery, possibly followed by adjuvant therapy such as immunotherapy, targeted therapy, or radiation therapy.
• Sources: American Cancer Society, Mayo Clinic

Stage IV

• Description: Melanoma has spread to distant lymph nodes or other organs such as the lungs, liver, brain, or bones.
• Implications: This is the most advanced stage of melanoma. Treatment options may include surgery, immunotherapy, targeted therapy, radiation therapy, and palliative care to manage symptoms.
• Sources: American Cancer Society, National Cancer Institute

Sources for Further Reading

• American Cancer Society: Melanoma Skin Cancer Stages
• National Cancer Institute: Melanoma Treatment (PDQ®)
• Mayo Clinic: Melanoma Stages

Understanding the stages of melanoma helps patients and healthcare providers decide on the best treatment strategies and understand the prognosis. Early detection and treatment significantly improve outcomes.