Background: In-transit metastasis is an important morbidity factor after sentinel lymphonodectomy (SLNE). So far, factors posing an increased risk after SLNE have not been adequately analyzed.
Methods: Using Kaplan-Meier estimations and the Cox proportional hazards model, we analyzed the risk of developing in-transit metastases after SLNE for 328 consecutive patients (median tumor thickness, 2.0 mm; median follow-up period, 40 months).
Results: The 5-year probability of developing in-transit metastases as a first recurrence was 11.2%. After negative and positive SLNE, the probabilities were 6.3% and 24%, respectively. Patients in whom satellite metastases were excised concurrently with the primary tumor had a probability of recurrence with in-transit metastases of 41%. In sentinel lymph node (SLN)-negative patients with primary tumors having a thickness of more than 4 mm, the probability was 22.1%. Among the group of SLN-positive patients, significantly increased in-transit probabilities were observed in those with primary tumors that were thicker than 4 mm (41.8%), with tumors located on the distal extremities (42.1%), and with penetration of the nodal metastasis of >1 mm into the SLN (36%) and in patients with capsular breakthrough (63.3%). By using multifactorial analysis, the SLN status (P = .005), Breslow thickness (P = .0009), and extremity location of the primary melanoma (P = .005) significantly predicted the risk of in-transit recurrence. Satellite metastasis (P < .089), Clark level, and ulceration did not reach significance.
Conclusions: Subgroups of patients can be identified who seem to have an increased risk of developing in-transit metastases as a first recurrence after SLNE. Individualized therapeutic strategies should be developed for these patients.