Role of sentinel lymphadenectomy in thin invasive cutaneous melanomas

Purpose: Regional lymph node status is the strongest prognostic determinant in early-stage melanoma. Lymphatic mapping and sentinel lymphadenectomy (LM/SL) is standard to stage regional nodes because it is accurate and minimally morbid, yet its role for thin (less than or equal to 1.5 mm) primary melanomas is unknown. Patients and Methods: Our melanoma database of more than 10,000 patients was reviewed for patients with melanomas less than or equal to 1.50 mm thick who underwent LM/SL. All had lymphoscintigrams and LM/SL via dye alone or with radiopharmaceutical. Patients with tumor-positive sentinel nodes (SNs) underwent completion dissections. Results: Five hundred twelve patients underwent LM/SL. Most were men (57%), and median age was 49 years. Most primary melanomas were on the torso (44%). Twenty-five patients (4.9%) had tumor-positive SNs. The thinnest lesion with a nodal metastasis was 0.35 mm. The SN-negative and SN-positive cohorts were equivalent by sex, but SN+ patients tended to be younger (P = .053), with significantly more SN metastases in those younger than 44 years (P = .005). No consistent pathology among SN-positive primary melanomas was found. Among those with 1.01- to 1.05-mm primaries, 7.1% were SN-positive. Among 272 patients with lesions less than or equal to 1.00 mm, 2.9% had positive SNs and 1.7% with lesions less than or equal to 0.75 mm had SN metastases. All 13 deaths were in SN-negative patients. Median follow-up durations in SN-positive and SN-negative patients were 25 and 45 months, respectively. Conclusion: The high nodal positivity rate associated with primary melanomas 1.01 to 1.50 mm thick suggests that LM/SL is indicated in this group. Younger age may be correlated with nodal metastases in patients with lesions less than or equal to 1.00 mm. Lesions less than or equal to 0.75 mm have minimal metastatic potential, and therefore LM/SL is rarely indicated. (C) 2003 by American Society of Clinical Oncology.