In the univariate Cox proportional hazards regression model, patients with either a BRAF or NRAS mutant tumour had an increased risk of developing recurrence following a negative SLNB compared to patients with wild-type tumours (HR = 1.40); however, unadjusted, this did not reach statistical significance (95% CI 0.76–2.59, p = 0.3). This evidence concerns the gene NRAS and neoplasm.