Is completion lymphadenectomy after a positive sentinel lymph node biopsy for cutaneous melanoma always necessary?

HYPOTHESIS Completion lymph node dissection (CLND) has usually been recommended after metastatic disease is identified in the sentinel lymph node (SLN) biopsy to eradicate further metastases in nonsentinel nodes. We hypothesized that patients with negative lymph nodes included in the initial SLN specimen have low risk of metastases in the residual draining basin and may not require CLND. DESIGN Chart review. SETTING University-affiliated tertiary care referral center. PATIENTS Between January 1, 1997, and May 31, 2003, 506 consecutive patients underwent SLN biopsy for staging of primary cutaneous melanoma. INTERVENTION The SLN biopsy identified 87 patients (17.2%) with metastatic melanoma, of whom 80 underwent CLND. RESULTS In 28 patients, all SLNs were found to contain metastatic melanoma. Seven (25%) of these patients had additional metastases identified in the CLND specimen. In 52 patients, 1 or more SLNs did not contain metastatic melanoma. Five (10%) of these patients had additional metastases in the CLND specimen (P =.02). CONCLUSIONS Although no evidence of metastatic melanoma was found on CLND in most patients in whom negative nodes had been removed with positive SLNs at the initial biopsy, 10% of these patients did have further metastases. This subgroup of patients (positive SLNs and negative nodes in the SLN biopsy specimen) is at significantly lower risk for further metastasis, but CLND cannot be safely omitted even for these patients.