Predicting sentinel and residual lymph node basin disease after sentinel lymph node biopsy for melanoma

BACKGROUND. The selection of patients for sentinel lymph node biopsy (SNB) and selective lymphadenectomy for histologically positive sentinel lymph no des (SLND) are areas of debate. The authors of the current study attempted to identify predictors of metastases to the sentinel and residual nonsentin el lymph nodes in patients with melanoma. METHODS. The Indiana University Interdisciplinary Melanoma Program computer ized database was queried to identify all patients who underwent SNB for cl inically localized cutaneous melanoma. Demographic, surgical, and histopath ologic data were recorded. Univariate and multivariate logistic regression analyses were performed to identify associations with SNB and nonsentinel l ymph node positivity. Classification tree and logistic procedures were perf ormed to identify the ideal tumor thickness cutpoint at which to perform SN B. RESULTS, Two hundred seventy-five SNB procedures were performed to stage 34 8 regional lymph node basins for occult metastases from melanoma. Of the 27 5 melanomas, 54 (19.6%) had a positive SNB, as did 58 of 348 basins (16.7%) . Classification and logistic regression analysis identified a Breslow dept h of 1.25 mm to be the most significant cutpoint for SNB positivity (odds r atio 8.8:1; P = 0.0001). By multivariate analyses, a Breslow thickness cutp oint greater than or equal to 1.25 mm (P = 0.0002), ulceration (P = 0.005), and high mitotic index (> 5 mitoses/high-power field; P = 0.04) were signi ficant predictors of SNB results. SLND was performed in 53 SNB positive pat ients, 15 of whom (28.3%) had at least 1 additional positive lymph node. SL ND positivity was noted across a wide range of primary tumor characteristic s and was associated significantly with multiple positive SN, but not with any other variable. SNB result correlated significantly with disease free a nd overall survival. CONCLUSIONS, Patients with a Breslow tumor thickness greater than or equal to 1.25 mm, ulceration, and high mitotic index are most likely to have posi tive SNB results. SLND is recommended for all patients after positive SNB b ecause it is difficult to identify patients with residual lymph node diseas e. (C) 2000 American Cancer Society.