[An individualized prognosis for truncal melanoma? A series of 77 cases]

Truncal melanoma is characterized by lymphatic drainage to single or multiple basins, affecting different anatomic regions. Since the introduction of sentinel lymph node biopsy (SLN) several questions have aroused in regard to this particular drainage. However, published data available on SLN anatomic distribution and on the prognostic value of multiple-nodal drainage is controversial. The aim of the present study was to provide further evidence based on our own experience.

From January 2003 through December 2006, a total of 77 melanoma of the trunk were diagnosed and treated at our institution. Systematic lymphoscintigraphy was obtained for all patients, followed by removal of SLN and in-transit lesions. When SLN metastasis was detected a complete lymphadenectomy was performed and adjuvant immunotherapy with interferon was administered. Statistical analysis was performed using Chi2 and Fisher's exact tests for categoric variables and Kaplan-Meier curves for survival.

Lymphoscintigraphy visualized 70.1% of single and 28.6% of multiple-nodal drainage (uninterpretable data). The rate of SLN macrometastasis ranged from 7.8 to 14.3%. Micrometastasis were found in 6.5% of patients. Positive SLN were discovered in 12.9% (17/54) of single-nodal and 18.6% (2/22) of multiple-nodal drainage. Melanoma's topography significantly influenced lymphatic drainage distribution, with 28.6% of single-nodal and 71.4% of multiple-nodal drainage for central tumors, and with 79.4% of single-nodal and 19.1% of multiple-nodal drainage for lateral tumors. The group with multiple-nodal drainage was associated non-significantly with primary tumor ulceration, 39 vs 24%. The Breslow thickness did not associate to multiple-nodal drainage. There were no differences in the rate of lymph node metastasis between both groups, 18 vs 12.9%. After a median follow-up of 47 months, prognosis was similar regardless of SLN status, with 80.3% overall survival for negative SLN and 81.3% for positive SLN. Single or multiple drainage did not affect survival rates significantly, with 84% survival for single-nodal drainage and 95% for multiple-nodal drainage.

Primary tumor location (medial location) was the principal risk factor for multi-nodal drainage: lymphoscintigraphy was the best technique for lymphatic drainage assessment. Primary tumor location with single or multi-nodal drainage did not influence the rate of positive SLN and had similar disease-free and overall survival. For us, truncal melanoma has not a different prognosis than melanoma of extremities.