CancerQuest | Skin Cancer: Melanoma Staging

Pathology Report & Staging
Staging is a powerful tool for treatment plan development and risk assessment in individual patients. Staging also enables physicians to communicate with each other regarding patients' diseases and insure equal standards of care for patients with similar disease states. ⁽¹⁾ The American Joint Committee on Cancer (AJCC) has developed a staging system for nonmelanoma and melanoma skin cancer.⁽²⁾

Staging of skin cancer is based on the TNM staging described in the CancerQuest section on Cancer Staging. Using this information, physicians may determine the stage of disease. The information below is specific for melanoma:

Stage I: The disease is localized to a primary tumor site. The majority of diagnoses are during this stage.⁽¹⁾
Stage II: The disease is more developed, but remains localized to the original site.⁽³⁾
Stage III: The disease has spread regionally; doctors often examine the number and location of invaded lymph nodes. ⁽¹⁾
Stage IV: The melanoma has spread to distant organs.⁽¹⁾

Several different approaches to staging of melanoma have been developed. Two criteria that have been used extensively include the categorization of melanomas according to their 'Clarks' levels' or 'Breslow thickness'. The Clark level is based on the layers of epidermis that the tumor has penetrated at the time of measurement. Breslow thickness measures the absolute distance of tumor penetration into the epidermis (measured in millimeters (mm)).

The Breslow tumor thickness evaluation system measures tumor thickness in mm from the top of the granular layer to the deepest tumor growth. The Breslow scale divides melanomas into four classes:

T1 1mm or less; "Thin melanoma"
T2 1-2 mm
T3 2-4 mm
T4 greater than 4mm depth; "Thick lesions"⁽⁴⁾⁽⁵⁾

The "Clark levels of invasion" system, named after the developer, pathologist, Wallace Clark, was the first widely accepted method for staging of melanomas. It is considered a reliable staging system today, and tumors are classified as one of five categories. It is important to note that Clark levels are NOT the same as the stage of the disease.

Level I Lesions: Melanoma restricted to the epidermis also known as an in situ melanoma.
Level II Lesions: Melanoma crosses the epidermis and invades the papillary dermis. This may be referred to as the micro invasive radial growth phase.
Level III Lesions: The entry into the true tumor phase in which the tumor grows to fill the papillary dermis region. Such tumors have entered the vertical growth phase.
Level IV Lesions: Tumor cells overcome barriers of the papillary dermis- reticular dermis barrier, invading the reticular dermis region.
Level V Lesions: Tumor growth extends into the subcutaneous fat.⁽⁴⁾⁽⁵⁾

More advanced disease is generally associated with a decreased survival rate.⁽¹⁾

View detailed staging information from the National Comprehensive Cancer Network (NCCN).

References for this page:

Petro A, Schwartz J, Johnson T. "Current melanoma staging." Clinical Dermatology. 2004 May-Jun;22(3):223-7. [PUBMED]
Rager EL, Bridgeford EP, Ollila DW. "Cutaneous melanoma: update on prevention, screening, diagnosis, and treatment." American Family Physician. 2005 Jul 15;72(2):269-76. [PUBMED]
American Cancer Society. Cancer Facts & Figures 2010. Atlanta: American Cancer Society; 2010. [http://www.cancerquest.org/multimedia/pdf/facts&figures2010.pdf]
Lomuto M, Calabrese P and A Giuliani. "Prognostic signs in melanoma: state of the art." 2004 18(3):291-300. [PUBMED]
Elder DE, Gimotty PA, D Guerry. "Cutaneous melanoma: estimating survival and recurrence risk based on histopathologic features." 2005 Dermatol Ther. 18(5):369-85. [PUBMED]