Molecular and demographic landscape of advanced cutaneous melanoma: A 10-year experience of a national reference laboratory in Colombia (2014–2023).

Abstract

e21523 Background: Cutaneous melanoma (CM) exhibits significant biological heterogeneity. While BRAF V600 mutations are reported in 40-50% of cases globally, their frequency varies by ethnicity. In Latin America, subtypes like acral lentiginous and mucosal melanoma are more prevalent, presenting distinct mutational profiles. We characterized the BRAF status and demographics of a large cohort processed at a National Reference Laboratory to address the regional data gap in precision oncology. Methods: A retrospective observational study was conducted on 604 patients with advanced CM (Stages III-IV) whose samples were centralized and processed at a single reference unit (UDHO) in Cali, Colombia. BRAF mutations in Exon 15 (codons 600-601) and Exon 11 (codons 466-469) were detected using qPCR with IVD/CE certified kits. DNA was extracted from FFPE tissue with a minimum neoplastic content of 10%, analyzed via automated software (Oncology Life Science Research) to ensure standardization. Results: The cohort (n = 604) showed a nearly balanced sex distribution (51.5% male, 48.5% female). Patient age ranged from 12 to 90 years, with 76.8% of the population being older than 50 years at diagnosis. BRAF mutations were identified in 26.7% of valid cases, while 67.5% were wild-type. Among mutated cases, V600K was specifically identified in 14.3%. Notably, a marked health equity gap was observed: 94.4% of molecular tests were sponsored by the pharmaceutical industry, with only 5.6% covered by national health entities. The invalid result rate was low (5.8%), reflecting high pre-analytical quality. Conclusions: The population analyzed at this National Reference Laboratory presents a distinct molecular signature with a significantly lower BRAF mutation rate (26.7%) than global averages. This 10-year experience underscores the importance of centralized high-quality testing to identify regional genetic particularities. Our findings highlight a major health equity challenge, as diagnostic access remains heavily dependent on industry sponsorship, and emphasize the need for tailored therapeutic strategies in the Colombian population.