Varying Mutational Alterations in Multiple Primary Melanomas

Area of Science:

• Oncology
• Genetics
• Dermatology

Background:

• The mitogen-activated protein (MAP) kinase pathway is critical in melanoma oncogenesis.
• Multiple primary melanomas (MPMs) occur in up to 8% of patients, with limited understanding of their genetic diversity.
• TERT-promoter mutations are an additional genetic alteration identified in melanoma.

Purpose of the Study:

• To investigate the mutational status of BRAF, NRAS, and TERT promoter genes in patients with MPMs.
• To assess the genetic diversity and concordance of mutations across multiple primary melanomas.
• To determine the diagnostic and therapeutic implications of genetic alterations in MPMs.

Main Methods:

• Genotyping of BRAF, NRAS, and TERT promoter mutations in 237 malignant melanomas from 96 patients with MPMs.
• Correlation of mutation patterns with clinicopathological characteristics.
• Prognostic impact assessment using Cox regression analysis.

Main Results:

• BRAF mutations in 35.4%, NRAS mutations in 14.0%, and TERT-promoter mutations in 47.3% of melanomas.
• Mutation patterns were discordant in 61.4% of patients between first and subsequent primary tumors.
• NRAS mutation showed a significant negative prognostic impact on time to progression and distant metastasis-free survival.

Conclusions:

• The majority of primary melanomas in patients with MPMs exhibit discordant BRAF, NRAS, and TERT-promoter genotypes.
• Molecular testing for targeted therapy should be performed on metastatic tissue, not primary tumors, due to genetic heterogeneity.
• Understanding genetic diversity in MPMs is crucial for effective patient management and treatment strategies.