Molecular Profiling of Archival Tonsillar Squamous Cell Carcinoma in a Korean Pre-HPV-vaccination Cohort

Tonsillar squamous cell carcinoma (TSCC) is a biologically heterogeneous malignancy in which human papillomavirus (HPV) infection, epidermal growth factor receptor (EGFR) alteration, and chromosomal instability represent major oncogenic mechanisms. This study evaluated HPV genotyping, EGFR mutation, and loss of heterozygosity (LOH) at chromosomal loci 17p13 and 9q22 in archival TSCC using conventional polymerase chain reaction (PCR)-based methodologies reproducible without next-generation sequencing infrastructure. The cohort, collected between 2000 and 2006 prior to the implementation of national HPV vaccination programs in Korea, represents a rare pre-vaccination molecular reference dataset from an East Asian population.

Forty cases of TSCC diagnosed between 2000 and 2006 were analyzed. HPV genotyping was performed using type-specific PCR covering 21 HPV genotypes. LOH analysis was conducted using microsatellite markers targeting 17p13 and 9q22. EGFR mutations in exons 18-21 were assessed by Sanger sequencing. Associations among molecular alterations and clinicopathological parameters were analyzed using chi-squared testing.

HPV positivity was identified in 18 out of 40 cases (45.0%). HPV-16 and HPV-18 were the predominant genotypes, accounting for 76.2% of all detected HPV genotype identifications. LOH was detected in 57.5% of cases at 17p13 and 45.0% at 9q22. EGFR mutations were identified in 17.5% of tumors. No significant associations were observed among HPV status, EGFR mutation, LOH events, or TNM stage. Notably, EGFR mutations were also observed in a subset of HPV-positive tumors, suggesting partially independent oncogenic pathways.

This archival Korean TSCC cohort demonstrates molecular heterogeneity involving HPV-associated carcinogenesis, EGFR-mediated signaling, and chromosomal instability. The findings provide a rare pre-vaccination molecular baseline from an East Asian population and demonstrate the feasibility of integrated PCR-based molecular profiling in settings without advanced genomic infrastructure.