No abstract

SUMMARY Oncogenic BRAF mutations are more frequent in cutaneous melanoma from sites with little or moderate sun-induced damage than from sites with severe cumulative solar ultraviolet (UV) damage. We studied cutaneous melanomas from geographic regions with different levels of ambient UV radiation to delineate the relative effects of cumulative UV damage, age and anatomic site on the frequency of BRAF mutations. We show that BRAF-mutated melanomas occur in a younger age group on skin without marked solar elastosis, and less frequently affect the head and neck area, compared to melanomas without BRAF mutations. The findings indicate that BRAF-mutated melanomas arise early in life at low cumulative UV doses, whereas melanomas without BRAF mutations require accumulation of high UV doses over time. The effect of anatomic site on the mutation spectrum further suggests regional differences among cutaneous melanocytes.

Summary Melanoma is comprised of biologically distinct subtypes. The defining clinical, histomorphologic and molecular features are not fully established. This study sought to validate the association between genetic and histomorphologic features previously described, determine their reproducibility, and association with important clinical variables. Detailed clinical and histomorphologic features of 365 primary cutaneous melanomas were assessed by 11 pathologists and correlated with mutation status of BRAF and NRAS. There was substantial agreement in the quantitative assessment of histomorphologic features showing similar or better interobserver reproducibility than the established WHO classification scheme. We confirmed that melanomas with BRAF mutations showed characteristic morphologic features (p<0.0001) and metastasized more frequently to regional lymph nodes (p=0.046). Importantly, melanomas without mutations were a heterogeneous group, with a subset having very similar features clinical and morphological features than those with BRAF mutation raising the possibility that they are biologically related. Our study confirms an association between histomorphologic features, mutation status and pattern of metastasis, providing criteria for a refined melanoma classification aimed at defining biologically homogeneous disease subgroups.

No abstract

SummaryInherited MC1R variants modulate MITF transcription factor signaling, which in turn affects tumor cell proliferation, apoptosis, and DNA repair. The aim of this BioGenoMEL collaborative study in 10 melanoma cohorts was to test the hypothesis that inherited variants thereby moderate survival expectation. A survival analysis in the largest cohort (Leeds) was carried out adjusting for factors known to impact on survival. The results were then compared with data from nine smaller cohorts. The absence of any consensus MC1R alleles was associated with a significantly lower risk of death in the Leeds set (HR, 0.64; 95% CI, 0.46–0.89) and overall in the 10 data sets (HR, 0.78; 95% CI, 0.65–0.94) with some support from the nine smaller data sets considered together (HR, 0.83; 95% CI, 0.67–1.04). The data are suggestive of a survival benefit for inherited MC1R variants in melanoma patients.