Predictors and natural history of in-transit melanoma after sentinel lymphadenectomy

Background: In-transit recurrence is a unique and uncommon pattern of treatment failure in patients with melanoma. Little information exists concerning the incidence, predictors, and natural history of in-transit disease since the introduction of sentinel lymph node biopsy (SLNB). Methods: Between 1991 and 2001, 1395 patients with primary melanoma Underwent SLNB. Univariate and multivariate logistic regression analyses were performed to examine the association among known clinicopathologic factors, in-transit recurrence, and distant metastatic failure after the development of in-transit disease. Results: With a median follow-up of 3.9 years, 241 patients (17.3%) experienced disease recurrence, including 91 (6.6%) who developed in-transit recurrence. Independent predictors of in-transit recurrence included age > 50 years. a lower extremity location of the primary tumor. Breslow depth, ulceration, and sentinel lymph node (SLN) status. Of the 69 patients who presented with in-transit disease as the sole site of first recurrence, 39 developed distant disease. By univariate analysis, predictors of distant failure among patients with in-transit disease included SLN status, largest metastatic focus in the SLN > 2.5 mm(2), subcutaneous location of in-transit disease, in-transit tumor size >= 2 cm, and a disease-free interval before in-transit recurrence of < 12 months. In-transit tumor size remained a significant predictor of distant metastasis by multivariate analysis (odds ratio, 9.69). Conclusions: The overall incidence of in-transit metastases in patients undergoing SLNB is low and does not seem to have increased since the introduction of the SLNB technique. In-transit recurrence, as well as subsequent distant metastatic failure, can be predicted on the basis of adverse tumor factors and SLN status.