BRAF, C-KIT, and NRAS mutations correlated with different clinicopathological features: an analysis of 691 melanoma patients from a single center

BACKGROUND: Discrepancies in genetic alterations found in melanoma are conspicuous between different ethnic groups. With the approval of BRAF- and MEK-targeted inhibitors in China, it is necessary to further elucidate the landscape of gene mutation in Chinese melanoma patients. METHODS: The frequency and distribution of BRAF, C-KIT, and NRAS mutations in 691 melanoma patients was determined, and the statistical significance of correlations between different gene mutations and clinicopathological features was analyzed. RESULTS: Among a total of 691 patients, BRAF mutation was found in 166 patients (24.0%), and V600E was the prominent genetic alteration (145/166, 87.3%). Statistical analyses showed that younger patients (<60) had a higher BRAF mutation rate than older patients (≥60, P=0.000), and the frequency of BRAF mutation was more likely to be lower in patients with the following: melanoma located in an extremity (P=0.000), acral-lentiginous melanoma subtype (P=0.000), thinner melanoma thickness (P=0.047), and no ulceration (P=0.030). The frequency of NRAS mutation was 12.6% (38/302), and primarily involved codon 61 in exon 3 and codon 12 in exon 2. Mutation of C-KIT was detected in 65 patients (9.4%), and the most common site of mutations was L576 in exon 11 (29/65, 44.6%). Patients with NRAS or C-KIT mutation had higher Clark level (P=0.035 and 0.047, respectively) and were more likely to have melanoma located in an extremity (P=0.003 and 0.009, respectively) than those without such mutation. The concordance of gene mutations between paired primary and metastatic lesions was 89.6% (60/67), and visceral metastases showed the highest distribution of gene mutations versus primary melanomas (100.0%) compared with lymph nodes (90.9%) and cutaneous metastases (83.3%). CONCLUSIONS: In this large cohort of Chinese melanoma patients, the frequencies of BRAF and NRAS mutations were lower than those observed in Caucasian cohorts, but the clinicopathological features of BRAF, C-KIT, and NRAS mutation were consistent. Paired primary and metastatic lesions showed high concordance of gene mutations.