BRAF (V600E) gene mutation in patients with thyroid cancer in Sri Lanka: A pilot study

Thyroid cancer (TC) is the most common endocrine malignancy worldwide. Occasionally, inadequate treatment of malignancies and overtreatment of benign conditions result due to inconclusive diagnosis, while poor clinical outcomes occur due to cancer recurrence or resistance to existing therapies. Elucidation of the molecular genetic basis of TC potentiates its diagnosis and treatment. BRAF(V600E) is a commonly occurring mutation in TC. This retrospective cross-sectional study was undertaken to determine the prevalence of this mutation in a cohort of Sri Lankan TC patients. DNA was extracted from formalin-fixed paraffin-embedded (FFPE) thyroid tissue samples (malignant subtypes, n = 50 (papillary, follicular, medullary, anaplastic, and oncocytic thyroid carcinomas); benign type, follicular adenoma, n = 26) using the phenol-chloroform method. Mutant allele specific PCR (sensitive to 1-5% mutant allele detection in a wild-type background) amplified BRAF wild-type, and mutant alleles. Genotypes were established by visualizing PCR amplicons (125 bp) of each allele type on agarose gels. Based on the allele specific PCR used for molecular diagnosis, most of TC patients in the study population (n = 68) were of the heterozygous genotype. One individual with papillary TC was homozygous for the mutant allele, and the remaining seven were homozygous for the wild-type allele. As this mutation was not restricted to malignant subtypes in comparison to the benign subtype (p > 0.05), its applicability as a diagnostic marker remains contentious. These preliminary findings underpin the potential for optimizing TC management through molecular diagnosis using available targeted therapy.