Melanoma Staging and Treatment Approach

Staging System

• The American Joint Committee on Cancer (AJCC) TNM classification system (8th edition) is the standard staging system for melanoma, with treatment approaches tailored to stage including wide local excision for localized disease, sentinel lymph node biopsy for intermediate thickness tumors, and systemic therapies for advanced disease 1

Stage Grouping

• The National Comprehensive Cancer Network recommends stage grouping as follows: Stage 0 for melanoma in situ, Stage I-II for localized disease with varying thickness and ulceration status, Stage III for regional nodal metastases or in-transit/satellite metastases, and Stage IV for distant metastases 2

Treatment Approach by Stage

• The American Joint Committee on Cancer recommends wide local excision with safety margins based on tumor thickness: 0.5 cm for in situ melanomas 3, 1 cm for tumors ≤2 mm thick 4, and 2 cm for tumors >2 mm thick 4
• Sentinel Lymph Node Biopsy (SLNB) is recommended for intermediate thickness melanomas (>1 mm) 4 and thinner melanomas with adverse features (ulceration, high mitotic rate) 2
• Complete Lymph Node Dissection may be indicated for patients with clinically apparent nodal disease 2

Advanced Disease Management

• Molecular testing for actionable mutations is mandatory for resectable or unresectable stage III or IV disease, including BRAF testing and testing for NRAS and c-kit mutations if BRAF wild-type 1
• Different melanoma subtypes have different mutation profiles: cutaneous (BRAF, CDKN2A, NRAS, TP53) 3, acral (BRAF, NRAS, NF1, KIT) 3, and mucosal (SF3B1) 1
• Targeted therapy is recommended for patients with BRAF mutations 1

Clinical Evaluation and Follow-up

• Initial evaluation should include complete skin examination and attention to lymph node drainage basins 2
• Imaging studies are recommended based on stage, but not necessary for low-risk melanomas (tumor thickness <1 mm) 4

Common Pitfalls and Caveats

• Mitotic rate is no longer used for T1 staging but remains an important prognostic factor that should still be reported 1
• Proper documentation of sentinel node findings is critical, including size and location of tumor in positive nodes 2
• PD-L1 expression can be useful to assess but has limited clinical utility at this time 1
• Melanoma subtypes have different mutation profiles and may require different treatment approaches 1