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

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).

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.

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 mm2, subcutaneous location of in-transit disease, in-transit tumor size > or = 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).

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.