Utility of sentinel lymph node biopsy for solitary dermal melanomas.

BACKGROUND AND OBJECTIVES: Solitary dermal melanoma (SDM) is melanoma confined to subcutaneous and/or dermal layers in the absence of a known primary cutaneous lesion. We hypothesized that sentinel node biopsy is an effective staging strategy for this rare disease.
METHODS: A Markov decision model was constructed to represent two management strategies for SDM: wide local excision followed by observation, and wide local excision followed by sentinel node biopsy. Utilities, likelihood of positive sentinel node biopsy, and cancer progression rates during a five year time horizon were assigned based on institutional data and a review of existing literature. Estimated costs were derived using Medicare reimbursements.
RESULTS: Excision followed by sentinel node biopsy provides greater utility, yielding 3.85 discounted quality-adjusted life years (dQALY) compared to 3.66 for excision alone. The incremental cost-effectiveness ratio for sentinel node biopsy is $19,102 per dQALY. Sensitivity analyzes demonstrated that observation is more cost-effective if greater than 23% of sentinel node biopsies are positive (16% reported), or if 5-year survival for observed patients is greater than 76% (69% reported).
CONCLUSIONS: Based on existing clinical evidence, sentinel node biopsy yields greater utility than excision alone and is cost-effective for patients presenting with solitary dermal melanoma.