Prevalence of BRAF and NRAS mutations in cutaneous melanoma patients in Taiwan.

Abstract

BRAF and NRAS mutations have been described in melanomas among Caucasians and some Asian populations. However, few large-scale studies have investigated the status and clinical significance of BRAF and NRAS mutations in a Taiwanese population. Melanoma samples (n=119) were analyzed for mutations in exons 11 and 15 of the BRAF gene, and in exons 1 and 2 of the NRAS gene. The samples were studied in genomic DNA, using polymerase chain reaction amplification and Sanger sequencing. Mutations of the BRAF and NRAS genes were then correlated with clinicopathological features and patients' prognosis. The incidence of somatic mutations within the BRAF and NRAS genes was 14.3% (17/119 patients) and 10.1% (12/119 patients), respectively. Among the 17 patients with BRAF mutations, 15 (88.2%) had V600E mutations. BRAF mutation was frequently detected in younger patients (p=0.0035), in thin melanomas (p=0.0181), and in melanomas with less ulceration (p=0.0089). NRAS mutation was more often seen in patients with lymph node metastasis (p=0.0332). Both BRAF and NRAS mutations were not significantly correlated with overall survival and disease-free survival. As BRAF and NRAS mutations are rare in Taiwan, BRAF- or NRAS-targeted therapies may be effective only for selected Taiwanese melanoma patients.