Concordant BRAFV600E mutation status in primary melanomas and associated naevi: implications for mutation testing of primary melanomas
There is concern that BRAF mutant naevus cells admixed with melanoma cells could cause false positive mutation tests in BRAF wild-type melanomas. We sought to assess the frequency of BRAF(V600E) mutations in primary melanomas arising with/without associated naevi and determine BRAF(V600E) concordance between melanomas and associated naevi. Formalin fixed, paraffin embedded (FFPE) tissue from 57 patients with primary melanomas with/without associated naevi was immunohistochemically stained to detect BRAF(V600E) mutation. In a subset of patients (n = 29), molecular mutation testing was also carried out using a panel of 238 known genetic variants. Of the primary melanomas with an associated naevus (n = 29), 55% were BRAF(V600E) mutant with 100% concordance between the melanoma and associated naevus. In contrast, only 21% of the primary melanomas unassociated with naevi were BRAF(V600E) mutant (p = 0.009).Our results suggest that melanomas with associated naevi have a higher frequency of BRAF(V600E) mutations than melanomas unassociated with naevi. Furthermore, melanomas and their associated naevi were concordant in BRAF(V600E) status, which suggests that false positive mutation tests occurring as a consequence of admixed BRAF mutant naevus cells in BRAF wild-type primary melanomas are unlikely to be a problem in clinical practice. The findings have important implications for adjuvant clinical trials of targeted therapies.
|ISBN||1465-3931 (Electronic) 0031-3025 (Linking)|
|Authors||Kakavand, H.; Crainic, O.; Lum, T.; O'Toole, S. A.; Kefford, R. F.; Thompson, J. F.; Wilmott, J. S.; Long, G. V.; Scolyer, R. A.;|
|Published Date||2014-01-01 00:00:00|