Molecular alterations in clinical stage III cutaneous melanoma: Correlation with clinicopathological features and patient outcome

The aim of the present study was to evaluate the frequency and type of oncogenic v-raf murine sarcoma viral oncogene homolog B1 (BRAF)/neuroblastoma RAS viral (v-ras) oncogene homolog (NRAS) mutations in cutaneous melanoma with clinically detected nodal metastases (stage IIIB and C) in relation to clinicopathological features and outcome. The clinicopathological data of 250 patients following therapeutic lymphadenectomy (LND) between 1995 and 2010, as well as BRAF/NRAS mutational status in corresponding nodal metastases, were analyzed. The median follow-up time was 53 months. BRAF mutations were detected in 154 (62%) cases (141 p.V600E, nine p.V600K and four others) and mutually exclusive NRAS mutations were detected in 42 (17%) cases. The presence of a BRAF mutation was found to correlate with patients of a younger age. The five-year overall survival (OS) rate was 33 and 43% for LND and primary tumor excision, respectively, and the five-year disease-free survival (DFS) rate for LND was 25%. No correlation was identified between BRAF/NRAS mutational status and RFS or OS (calculated from the date of the LND and primary tumor excision); for BRAF- and NRAS-mutated melanoma, the prognosis was the same for patients with wild-type (WT) melanoma. The important factors which had a negative impact on OS and DFS were as follows: Male gender, >1 metastatic lymph node and extracapsular extension of nodal metastases. The interval between the diagnosis of the initial melanoma to regional nodal metastasis (median, 10 months) was not significantly different between BRAF-mutant and -WT patients. Our largest comprehensive molecular analysis of clinical stage III melanoma revealed that BRAF and NRAS mutational status is not a prognostic marker in stage III melanoma patients with macroscopic nodal involvement, but may have implications for potential adjuvant therapy.