Lymph node ratio predicts disease-specific survival in melanoma patients.

Abstract

The objectives of this analysis were to compare various measures associated with lymph node (LN) dissection and to identify threshold values associated with disease-specific survival (DSS) outcomes in patients with melanoma. Patients with lymph node-positive melanoma who underwent therapeutic LN dissection of the neck, axilla, and inguinal region were identified from the SEER database (1988-2005). We performed Cox multivariate analyses to determine the impact of the total number of LNs removed, number of negative LNs removed, and LN ratio on DSS. Multivariate cut-point analyses were conducted for each anatomic region to identify the threshold values associated with the largest improvement in DSS. The LN ratio was significantly associated with DSS for all LN regions. The LN ratio thresholds resulting in the greatest difference in 5-year DSS were .07, .13, and .18 for neck, axillary, and inguinal regions, respectively, corresponding to 15, 8, and 6 LNs removed per positive lymph node. After adjustment for other clinicopathologic factors, the hazard ratios (HRs) were .53 (95% confidence interval [CI], .40 to .71) in the neck, .52 (95% CI, .42 to .65) in the axillary, and .47 (95% CI, .36 to .61) in the inguinal regions for patients who met the LN ratio threshold. Among the prognostic factors examined, LN ratio was the best indicator of the extent of LN dissection, regardless of anatomic nodal region. These data provide evidence-based guidelines for defining adequate LN dissections in melanoma patients.