Sentinel node biopsy in malignant melanoma: Swedish experiences 1997-2005

The sentinel node biopsy (SNB) procedure is a multidisciplinary technique, invented to gain prognostic information in different malignant tumors. The aim of the present study was to study the cohort of patients with malignant melanoma, operated with SNB, from the introduction of the technique in Sweden, concerning the prognostic information retrieved and the outcome of the procedures. In Sweden all patients with malignant melanoma are registered at regional Oncological Centers. From these databases ten centers were identified, treating malignant melanoma and performing sentinel node biopsy. Consecutive data concerning tumor characteristics, outcome of the procedure and disease related events during the follow-up time were collected from these ten centers. All cases from the very first in each centre were included. The SNB procedure was performed in 422 patients with a sentinel node (SN) detection rate of 97%, the mean Breslow thickness of the primary tumors was 3.2 mm (median 2.4 mm) and the proportion of ulcerated melanomas 38%. Metastasis in the SN was found in 19% of the patients but there was a wide range in the proportion of SN metastases between the different centers (5-52%). After a follow-up of median 12 months of 361 patients, SN negative patients had better disease-free survival than SN positive (p<0.0001). A false negative rate of 14% was found during the follow-up time. In this study the surgical technique seemed acceptable, but the non-centralized pathology work-up sub-optimal. However, SNB was still found to be a significant prognostic indicator, concerning disease free survival.