Surgical management of the groin lymph nodes in melanoma in the era of sentinel lymph node dissection.

HYPOTHESIS: Intraoperative lymphatic mapping and sentinel lymphadenectomy (LM/SL) has become an increasingly popular surgical technique for staging the regional lymph nodes in early-stage melanoma. The technique of LM/SL has potentially great advantage for the groin, where the morbidity of superficial groin dissection or iliac dissection can be high. The surgical management of these basins is unknown for patients with tumor-positive sentinel lymph nodes (SNs).

DESIGN: Cohort of successive patients undergoing LM/SL over 18 years. Those patients found to have tumor-positive SNs underwent sentinel complete lymph node dissection. Postoperatively, patients were followed up on a routine basis with serial examinations and chest radiography. The median follow-up was 50 months.

SETTING: Tertiary cancer center.

PATIENTS: The technique of LM/SL was performed for 431 consecutive patients. Sentinal lymph nodes were identified in each case. Patients with tumor-positive SNs underwent sentinel complete lymph node dissection.

INTERVENTION: Cutaneous lymphoscintigraphy and blue dye with or without use of the gamma probe-directed LM/SL. Sentinel lymph nodes were examined by hematoxylin-eosin staining and immunohistochemistry staining with HMB-45 and S100 protein. Only patients with tumor-positive SNs had sentinel complete lymph node dissection. Main Outcome Measure Computer-assisted database with statistical analyses using log-rank tests and Cox regression models.

RESULTS: Of the 431 patients, 264 (61%) were women and the median age was 50 years (age range, 15-89 years). A majority (86%) of the primary tumors were on the lower extremities, 54% were of Clark level IV or V, and there was a mean +/- SD thickness of 1.89 +/- 1.59 mm (range, 0.30-14.00 mm). Ninety-three patients (21%) were found to have tumor-positive SNs. After LM/SL and sentinel complete lymph node dissection, 62 patients (67%) were found to have a single tumor-positive lymph node, 25 (27%) had 2 tumor-positive lymph nodes, and 6 (6%) had 3 or more tumor-positive lymph nodes. Only 12 patients (4%) with tumor-negative SNs have had recurrence in the dissected basin. The 5-year overall survival was significantly better for patients with tumor-negative lymph nodes (mean +/- SD 5-year overall survival, 94% +/- 5%) than for patients with tumor-positive lymph nodes (mean +/- SD 5-year overall survival, 75% +/- 4%) (P < .01). The tumor status of the Cloquet lymph node was predictive of the tumor status of the iliac lymph nodes. Multivariate analyses with a Cox regression model identified tumor-positive SN (P = .001), primary tumor thickness (P = .03), and ulceration (P = .001) as being predictive of survival. Sex, age, Clark level, and primary site were not significant (P > .05).

CONCLUSIONS: Our results demonstrate the prognostic significance of LM/SL for early-stage melanoma draining to the groin basin. The accuracy of LM/SL measured by the rare recurrences suggests that this surgical procedure should become standard for patients with early-stage melanoma of the lower extremities and trunk. Sampling of the Cloquet node should be used to determine the need for iliac dissection when a tumor-positive SN is identified in the groin.