Prognostic implications of thick (≥4-mm) melanoma in the era of intraoperative lymphatic mapping and sentinel lymphadenectomy

Background: Lymphatic mapping/sentinel lymphadenectomy (LM/SL) has become a routine part of our treatment algorithm for primary melanoma, yet its role in the management of thick (greater than or equal to4-mm) lesions is unknown. Methods: One hundred twenty-one patients with thick primaries underwent LM/SL at our institute. Survival curves were constructed from Kaplan-Meier estimates and analyzed by Cox proportional hazards methods. Results: Sixty-three percent of patients were men, median age 54 years. The primary tumor sites were trunk (46%), extremities (32%), and head and neck (21%). Primary thickness ranged from 4 to 15 mm (median, 6.0 mm). Forty-five percent of primary tumors were ulcerated. Thirty-five percent of patients had tumor-positive dissections. Median follow-up was 31 months. The overall 5-year survival was no different (P =.726) for ulcerated and nonulcerated lesions. There was no difference (P =.159) in overall survival after tumor-negative (60% +/- 7%) and tumor-positive (50% +/- 10%) dissections. The 5-year disease-free survival was significantly (P =.012) lower in patients with tumor-positive (34% +/- 9%) than tumor-negative (47% +/- 7%) dissections. Conclusions: Although LM/SL has become a popular technique for staging the regional lymph nodes in early-stage melanoma, our results suggest that sentinel node status is predictive of disease-free survival for thick primary tumors but is not yet reflective of overall survival. The role of LM/SL for patients with thick primary tumors is not clearly defined.