Should we report Breslow density, a new concept in cutaneous melanoma?

Breslow density is a newly defined biomarker, independent of Breslow thickness. We aimed to investigate the relationship of Breslow density with other clinicopathological prognostic factors and its effect on the overall survival and disease-free survival in patients with cutaneous melanomas.

This was a single-centre retrospective study of patients (n = 19) diagnosed with cutaneous malignant melanomas in our hospital between 2011 and 2019 were included in the study. The exclusion criteria were in situ melanomas, punch or incisional biopsies and metastasis at the time of the diagnosis. Breslow density was determined by reevaluating slides obtained at the time of the initial diagnoses. The effect of Breslow density on survival was determined using univariate and multivariate Cox proportional risk analyses.

In terms of the overall survival, mortality risk increased as Breslow density increased (p = 0.044). Breslow density was not significantly associated with the overall survival in the multivariate model (p = 0.078). In terms of disease-free survival, the risk of metastasis or recurrence increased 1.229- fold in accordance with an increase in Breslow thickness (CI: 1.057-1.428), whereas increased Breslow density increased the metastasis or recurrence risk 1.059-fold (CI: 1.008-1.112). In the multivariate model, only Breslow density was statistically significant (p = 0.046).

As a semi-quantitative and subjective measurement, Breslow density is not a completely accurate representation of the invasive tumour load. However, the measurement is practical and low cost and requires no additional equipment. Therefore, Breslow density can be measured in every laboratory. Considering the value of Breslow density in predicting the prognosis in patients with cutaneous melanomas and strong inter-observer compliance observed in the present study, we believe that it would be useful to include this measurement in pathology reports.