In-transit Melanoma Metastases: Incidence, Prognosis, and the Role of Lymphadenectomy

To analyze a large, single-institution database to further understanding of melanoma in-transit metastases (ITM) with regard to incidence, prognosis, and the role of lymphadenectomy.

A total of 11,614 patients with single primary cutaneous melanomas were treated at Melanoma Institute Australia between January 1994 and December 2009. Of these, 505 developed ITM. Clinicopathologic characteristics, sentinel node (SN) status, patterns of disease progression, and outcomes were analyzed.

In the 505 patients with ITM, the median primary tumor thickness was 2.95 mm, and 39.4 % were ulcerated. The ITM rates for patients with primary melanomas <1 or ≥1 mm in size and in those who underwent sentinel node biopsy were 0.4, 7.8, and 7.2 %, respectively. The ITM rates for SN-positive and SN-negative patients were 21.6 and 4.7 %, respectively. The median time from primary diagnosis to the development of ITM was 17.9 months. After ITM diagnosis, the median survival time was 19.9 months, 5-year survival was 32.8 %, and 10-year survival was 27.5 %. After ITM diagnosis, primary tumor site (head/neck, trunk) and ulceration were predictors of poorer survival. Five-year survival from the time of ITM ranged from 47.9 % for nonulcerated limb primary lesions to only 13.6 % for ulcerated trunk primary lesions. Elective lymph node dissection in clinically node-negative patients with ITM did not significantly alter overall survival.

This large study demonstrates that the diagnosis of melanoma ITM carries serious adverse prognostic implications and will assist in improving the accuracy of staging and prognostic estimates as well as treatment in these patients.