Highly Sensitive Multivariable Assay Detection of Melanocytic Differentiation Antigens and Angiogenesis Biomarkers in Sentinel Lymph Nodes With Melanoma Micrometastases

Objectives

To evaluate the prognostic value of melanocytic differentiation antigens and angiogenesis biomarkers in sentinel lymph nodes (SLNs) with melanoma micrometastases.

Design

Prognostic study of an inception cohort.

Setting

Academic research.

Patients

Between July 1, 1999, and July 31, 2002, all patients who had primary cutaneous or mucosal melanomas that have a Breslow depth of 1.5 mm or greater, ulceration, or Clark level IV or V, or had SLN biopsies.

Main Outcome Measures

By the use of quantitative reverse transcription–polymerase chain reaction, the expression of the following was analyzed in SLNs: 2 melanocytic differentiation antigens (tyrosinase [P17646] and melanoma antigen recognized by T cells [MART-1; Q16655]) and genes involved in angiogenesis (VEGF[NM_001025366] andVEGFR2[AF035121]), lymphangiogenesis (VEGFC[NM_005429],VEGFR3[X68203],LYVE1[NM_016164], andPROX1[002763]), and invasion (uPA[NM_002658],PAI1[NM_00602], andEMMPRIN[L10240]). Outcome measures were the association of these melanocytic differentiation antigens and angiogenesis biomarkers with clinicopathologic characteristics of patients, and an evaluation of the prognostic value for relapse-free survival and overall survival.

Results

Ninety-one patients were included, with a median follow-up period of 41 months. Micrometastases were present in 15% (14 of 91) of patients. Tyrosinase (P < .001), MART-1 (P < .001), vascular endothelial growth factor 121 (VEGF₁₂₁) (P = .007), andPAI1(P = .02) expression was significantly associated with micrometastasis. In univariate analysis, histologic findings and tyrosinase and MART-1 expression were significantly associated with relapse-free survival. Tyrosinase and MART-1 expression was associated with overall survival. A multiple Cox proportional hazards regression model identified negative histologic findings and tyrosinase expression that exceeded 27 copies/copy of TATA box-binding protein (third quartile) as significantly associated with an increased risk of relapse or death.

Conclusions

Quantitative assessment of melanocytic differentiation antigens in SLNs, which has prognostic value, is more specific than qualitative assessment. Prognosis may be more effectively predicted by the combination of quantitative assessment of melanocytic differentiation antigens in SLNs with histologic assessment. A significant association was found between the presence of micrometastases and the expression of angiogenesis biomarkers.