No non-sentinel node involvement in melanoma patients with limited Breslow thickness and low sentinel node tumour load

Aims: Most melanoma patients with a positive sentinel node (SN) undergo completion lymph node dissection and frequently experience associated morbidity. However, only 10-30% of SN-positive patients have further lymph node metastases. The aim of the present study was to predict the absence of non-SN metastases in a multicentre study of patients with a positive SN based on primary melanoma features and SN tumour load. Methods and results: Of 70 SN positive patients, 18 had non-SN metastases. Penetrative depth of metastatic cells into the SN and SN tumour load was assessed by morphometry. None of the 14 patients (20%) with a Breslow thickness <2.0mm and an SN tumour load <0.2mm ² had non-SN metastases. Similarly, none of the 15 patients (21%) with a Breslow thickness <2.0mm and SN penetrative depth <600μm had non-SN metastases. Lastly, none of the 14 patients (20%) with a Breslow thickness <2.0mm and a diameter of the largest SN deposit <500μm had non-SN metastases. Conclusions: A combination of limited Breslow thickness and low SN tumour load predicts absence of non-SN metastases in melanoma patients with a positive SN with high accuracy. We propose that this subgroup may be spared completion lymph node dissection.