Has the advent of modern adjuvant systemic therapy for melanoma rendered sentinel node biopsy unnecessary?

The prognostic value of sentinel node biopsy (SNB) is well established and SNB was therefore adopted as a requirement for pathological staging of melanomas>1 mm thick in the American Joint Committee on Cancer (AJCC) 8th edition. Consequently, a negative SNB status became an eligibility criterion for clinical trials of adjuvant systemic therapy in resected stage IIB/C melanoma. However, since the Keynote 716 trial demonstrated an improvement in relapse-free survival (RFS) in patients with Stage IIB/C melanoma, all of whom had SNB staging, some have argued that SNB is no longer required for patients with T3 and T4 primary melanomas. The rationale for omitting SNB is that these patients will be able to access adjuvant immunotherapy regardless of SNB status, avoiding the costs and potential complications of SNB. However, this argument overlooks the prognostic value of knowing a patient's nodal status and the therapeutic benefit of SNB in regional disease control. Based on extrapolation of data from multiple sources, we demonstrate that the risk of regional node-field relapse with SNB and immunotherapy for T3b and T4 melanomas is around 7-9% but is 20-27% without SNB. Similarly, the node-field recurrence rate with SNB alone is around 14% compared to around 40% with no SNB or immunotherapy. Consequently, in the absence of prospective data, we propose that the optimal management of the regional node-field for high-risk T3b and T4 primary melanomas is likely to be achieved by combining SNB and adjuvant immunotherapy for those patients who are suitable, rather than either treatment alone.