This study assessed the value of the radioisotopic method used alone, and factors influencing relapse rates, for sentinel lymph node (SLN) mapping in primary melanoma.Methods
One hundred and thirty-three patients with a diagnosis of melanoma (thickness greater than 0·75 mm) underwent γ probe-directed lymphatic mapping in a prospective single-centre study.Results
Mean Breslow thickness was 3 mm. At least one SLN was identified in 132 patients (mean 1·8 nodes per patient); the success rate was 99·2 per cent. Twenty-two patients (16·7 per cent) had a metastasis within the SLN. The mean tumour thickness in patients with a metastatic SLN was 4·4 mm compared with 2·7 mm for patients with a negative SLN (P < 0·001). The median time to recurrence was 20·4 months in SLN-negative patients compared with 8·5 months in those with SLN metastasis (P < 0·001). Ten (9·1 per cent) of the 110 SLN-negative patients developed recurrence. Three patients relapsed in the previously mapped lymphatic basin after a median follow-up of 27·1 months.Conclusion
This study confirmed the reliability and accuracy of SLN mapping using a radioisotope technique, and also the importance of the SLN as a predictive factor for survival. There was a low risk of locoregional recurrence when the SLN was not involved.