Baseline peripheral blood biomarkers including neutrophil-lymphocyte (NLR), platelet-lymphocyte (PLR) and lymphocyte-monocyte ratios (LMR) are associated with nodal status in a number of malignancies, but evidence is limited in cutaneous melanoma. This study investigated the association between baseline biomarkers and sentinel lymph node status in cutaneous melanoma.
 
This retrospective cohort study describes a consecutive series of patients who underwent wide excision and sentinel lymph node biopsy (SLNB) at a single institution over 10 years. Binary logistic regression was used to generate adjusted odds ratios (OR) and 95% confidence intervals (CI) for sentinel node involvement for each biomarker. 

Five hundred and sixty-nine cases who underwent SLNB had an available pre-operative blood result and were included. Factors associated with sentinel node positivity were increasing Breslow thickness, mitotic rate and tumour diameter, the presence of ulceration, microsatellites and vascular invasion and the absence of tumour infiltrating lymphocytes (p<0.05). An adjusted baseline NLR >1.9, PLR >180 and LMR <4.3 were associated with sentinel lymph node metastasis (OR 1·82 [95% CI 1·05, 3·17], p=0·034; 1·79 [1·02, 3·15], p=0·044 and 1·79 [1·06, 2·99], p=0·028, respectively). 

Baseline peripheral blood biomarkers appear to be associated with metastasis of melanoma to the sentinel node. Further investigation is required to validate this association.

Baseline neutrophil-lymphocyte, platelet-lymphocyte and lymphocyte-monocyte ratios are associated with microscopic metastases of cutaneous melanoma to the sentinel lymph node