Targeted molecular characterization of external auditory canal squamous cell carcinomas

Area of Science:

• Oncology
• Genomics
• Head and Neck Cancer

Background:

• External auditory canal squamous cell carcinomas (EAC SCCs) exhibit aggressive behavior and unique genomic profiles.
• Understanding EAC SCC molecular alterations is crucial due to their distinct anatomic site and recurrence rates.
• Genomic data for EAC SCCs are less characterized compared to cutaneous SCCs at other sites.

Purpose of the Study:

• To identify recurring and potentially targetable genomic alterations in primary EAC SCCs.
• To compare the mutational profiles of EAC SCCs with those of cutaneous SCCs from other head and neck subsites.
• To lay the groundwork for precise molecular characterization and improved treatment strategies for EAC SCC.

Main Methods:

• Targeted DNA sequencing of 7 primary EAC SCC specimens using a 227-gene panel.
• Extraction of genomic DNA from formalin-fixed paraffin-embedded tissues.
• Annotation of somatic and copy number alterations using validated bioinformatics pipelines.

Main Results:

• Recurrent alterations in TP53, EGFR, FGFR, and PIK3CA pathways were identified, similar to other head and neck cutaneous SCCs.
• High frequencies of telomerase reverse transcriptase amplification and DNA methyltransferase 1 alterations were observed.
• These latter alterations are rarely seen in cutaneous SCCs from other anatomical locations.

Conclusions:

• The study provides initial molecular insights into EAC SCC biology.
• Identified genomic alterations may contribute to the aggressive nature and unique characteristics of EAC SCC.
• This research is a foundational step towards precision medicine approaches for EAC SCC.