Identification rate, failure rate, false-negative rate and sensitivity of sentinel node biopsies performed in 292 skin melanoma patients

A false negative result of sentinel node biopsy is defined as nodal recurrence of the disease without previous local or in transit recurrence, within the same lymph node basin which has been found to be negative at previous sentinel node biopsy. Although false-negative results are the main pitfall of the method, only a few studies have been conducted to assess the scale of the issue. As the problem of false-negative results of SN procedures in skin melanoma patients was never addressed in our studies, we decided to critically assess the reliability of SN procedures performed at our department. The study was held at the Department of Surgical Oncology of the Medical University of Lodz. We studied two patient groups; the first, 'routine' group, was composed of 218 consecutive patients with skin melanoma, who underwent routine sentinel node procedure after the end of 'learning curve' period. The other, historical 'learning curve' group, was composed of our first 74 patients who underwent sentinel node procedure during the very beginning of the use of the method in our department. In both groups we assessed the successful identification rate of sentinel nodes, the failure rates, false-negative rates and the sensitivity of the method. The identification rate in the 'routine' group was 100% (218/218 patients), while it had been 95.9% (71/74 patients) in the 'learning curve' group. The failure rate in 'routine' group was 3.1% (6/192) and had been 10.2% (6/59) in 'learning curve' group. the false-negative rate in the 'routine' group was 18.7% (6/32) and had been 33.3% (6/18) in 'learning curve' group. The sensitivity of the sentinel node biopsy in the 'routine' group was 81.3% (26/32) and had been 66.7% (12/18) in the learning curve group. Our results suggest that the skill of the team performing SN-biopsy is of crucial importance. Nevertheless, despite the high skill of the team, the risk of missing the metastasis in sentinel node is considerable. This must be kept in mind during follow-up of SN-negative melanoma patients. (authors)