Significance of Multiple Lymphatic Basin Drainage in Truncal Melanoma Patients Undergoing Sentinel Lymph Node Biopsy

Background Truncal melanoma involving metastases to multiple lymph node basins has a much worse prognosis than tumor involvement of a single lymph node basin. Recent results also suggest that, independently of the status of lymph node involvement, patients with multiple lymphatic basin drainage (MLBD) on lymphoscintigraphy have an increased risk of lymph node metastasis and a worse prognosis than those with a single lymphatic drainage basin. Because published reports have conflicting results, the authors compared their experience at the University of Michigan Comprehensive Cancer Center with recently published findings.Methods The authors searched a prospectively maintained melanoma database at the University of Michigan for patients with primary truncal melanoma who underwent lymphoscintigraphy and sentinel lymph node biopsy between 1997 and 2004. The association of MLBD with the clinical and pathologic characteristics collected and the presence of regional metastases was tested by using contingency tables and the χ² test statistic and by using the Fisher’s exact test statistic when cell frequencies were small. The product-limit method of Kaplan and Meier was used to estimate disease-free and overall survival probabilities.Results Of 423 patients with primary truncal melanoma who underwent sentinel lymph node biopsy, 123 (29%) had a positive result, and 98 patients (23.2%) had MLBD. Patients with tumors located in the middle of the trunk and tumor ulceration were more likely to have MLBD (P < .0001 and P = .045, respectively). Patients with a single lymphatic drainage basin and MLBD had a similar risk of lymph node metastasis and similar disease-free and overall survival.Conclusions Patients with truncal melanomas tend to have MLBD when the tumor is located in the middle of the trunk or when ulceration is present. In our experience, drainage to multiple lymphatic basins was not an independent risk factor for sentinel lymph node metastasis and has no independent prognostic significance.