Characteristics Associated with Pathologic Nodal Burden in Patients Presenting with Clinical Melanoma Nodal Metastasis.

ABSTRACT

BACKGROUND: Nodal observation is safe for patients with microscopic melanoma metastasis in a sentinel lymph node (LN). Complete LN dissection (CLND) remains the standard of care for patients with clinically evident LN (cLN) metastases, even though about 40% have only one pathologic LN (pLN). We sought to identify clinical features associated with having one pLN among patients with cLNs. METHODS: Patients at three melanoma centers who underwent CLND for cLNs were identified. Clinicopathologic and imaging characteristics associated with one pLN were determined by multivariable logistic regression and classification tree analysis. RESULTS: Of 190 patients, 90 (47.4%) had one pLN and 100 (52.6%) had more than one pLN. By multivariable logistic regression, extremity versus truncal primary (odds ratio [OR] 2.15, p = 0.012), axillary versus superficial inguinal location (OR 3.89, p = 0.009), and preoperative cross-sectional imaging demonstrating more than one versus one cLN (OR 17.1, p < 0.001) were associated with more than one pLN. The negative predictive value for additional pathologic nodal disease of preoperative imaging was 70.9%, increasing to 74.4% for positron emission tomography/computed tomography. In the subgroup of patients with one cLN, the classification tree identified two groups with < 10% risk of additional pLNs (1) Breslow thickness > 6.55 mm (n = 17); and (2) if unknown primary or Breslow thickness ≤ 6.55 mm, then LN diameter > 1.8 cm in the inguinal location (n = 22). CONCLUSION: The majority of patients with one cLN from melanoma by preoperative imaging will harbor no additional pathologic nodes on CLND. Safety of nodal observation after clinical nodal excision in these patients, particularly in an era of effective adjuvant therapies, deserves prospective evaluation.