Sentinel lymph node biopsy in cutaneous melanoma: the WHO melanoma program experience

Background: We report the experience of the World Health Organization (WHO) Melanoma Program concerning sentinel lymph node (SLN) biopsy for detecting patients with occult regional nodal metastases to submit to selective regional node dissection. Methods: From February 1994 to August 1998, in 12 centers of the WHO Melanoma Program, 892 SLN biopsies were performed in 829 patients with clinical stage I melanoma (male: 370; female: 459; median age: 50 years old). The location of the primary melanoma was as follows: trunk 35%; lower limbs, 45%; upper limbs, 18%; and head and neck 2%. Blue dye injection for SLN identification was performed in all cases: preoperative lymphoscintigraphy was done in 440 patients, and an intra-operative probe for a radio-guided biopsy was used in 141 cases. Overall, the SLN identification rate was 88%. In 68% of the patients, only one SLN was identified, whereas two and three or more SLN were detected in 24% and 8% of the remaining cases, respectively. Results: Overall SLN positivity rate was 18%. intra-operative frozen section examination was performed in 39% of the cases and was helpful in detecting occult localizations only in 47% of the positive SLNs. Distribution of positive cases by primary thickness was as follows: < 1 mm: 2%; 1-1.99 mm: 7%; 2-2.99 mm: 13%; and greater than or equal to 3 mm: 31%. Positive nonsentinel lymph nodes were found in 22% of cases with positive SLN submitted for selective dissection. No complications due to the procedure were registered. Of 710 patients who were evaluated, 40 (6%) presented a regional nodal relapse after a negative SLN biopsy and underwent a delayed therapeutic dissection. From the 710 enrolled cases, 638 (88.5%) were alive without evidence of disease at the time of this writing. A multivariate analysis showed SLN status as one of the most significant prognostic factors (P = .000) along with thickness (P = .001) and ulceration (P = .015) of primary tumor. Conclusions: These data confirm the feasibility and safety of the SLN technique for selecting patients to submit to a radical node dissection. The data represent the basis for a future trial by the WHO Melanoma Program in this field to evaluate the most appropriate surgical approach for treating patients with occult regional nodal metastases.