From the Guidelines
Clark level 4 melanoma means the cancer has invaded into the reticular dermis, which is the deeper layer of the dermis (middle layer of skin). This classification system, developed by Dr. Wallace Clark, helps determine melanoma severity based on how deeply it has penetrated the skin layers. Clark levels range from 1 (most superficial) to 5 (deepest invasion). Level 4 indicates a more advanced stage where cancer cells have grown beyond the papillary dermis into the reticular dermis, but have not yet reached the subcutaneous fat (which would be level 5).
Key Points
- This depth of invasion is significant because deeper melanomas generally have a higher risk of metastasis (spreading to other parts of the body) 1.
- While Clark levels were historically important for melanoma staging, modern oncology now relies more heavily on Breslow thickness (measured in millimeters) for prognosis and treatment decisions.
- Patients with Clark level 4 melanoma typically require wide local excision surgery and may need sentinel lymph node biopsy to check if the cancer has spread to nearby lymph nodes.
- Additional treatments like immunotherapy or targeted therapy might be recommended depending on other factors such as tumor thickness, ulceration, and lymph node involvement 1.
- The management of melanoma is continually evolving, with new guidelines and recommendations being published regularly, such as the NCCN guidelines 1 and the UK guidelines 1.
- The decision to perform SLNB may be based on significant patient comorbidities, patient preference, or other factors, and SLNB is an important staging tool, but the impact of SLNB on overall survival is unclear 1.
From the Research
Melanoma Clark Level 4 Meaning
- Clark level 4 is a measure of the depth of invasion of melanoma, a type of skin cancer, as classified by the Clark level of invasion 2.
- The Clark levels of invasion are a system used to classify melanomas based on their depth of invasion into the skin, with level 1 being the least invasive and level 5 being the most invasive.
- A Clark level 4 melanoma is considered to be a more advanced stage of the disease, with the cancer having invaded deeper into the skin.
- The treatment for a Clark level 4 melanoma typically involves wide local excision of the tumor, with a margin of at least 2 cm, as well as assessment of the lymph nodes to determine if the cancer has spread 2, 3.
- The prognosis for a Clark level 4 melanoma is generally poorer than for earlier stages of the disease, with a higher risk of recurrence and metastasis.
- However, with prompt and appropriate treatment, it is possible to achieve a good outcome and improve survival rates 4, 5, 6.
Treatment and Prognosis
- The current recommendations for excisional removal of confirmed melanomas include 1-cm margins for lesions measuring 1.0 mm or less in thickness and 2-cm margins for lesions from 1.0 mm to 4.0 mm in thickness or Clark's level IV of any thickness 2.
- Sentinel lymph node biopsy (SLNB) is also an important part of the treatment and staging of melanoma, and can be performed after wide local excision (WLE) 5, 6.
- The accuracy of lymphatic mapping and SLNB after previous WLE has been demonstrated in several studies, with high rates of successful sentinel node identification and accurate reflection of the pathologic status of the draining lymph node basins 5, 6.