[Epidermal growth factor receptors: status evaluation methods and tumor expression]

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Targeted antitumor agents focus on the HER (human epidermal growth factor receptor) family of tyrosine kinase transmembrane receptors.
• Accurate target detection is crucial for effective therapeutic strategies against cancers involving HER family receptors.

Purpose of the Study:

• To evaluate established and emerging techniques for detecting HER2 and EGFR overexpression in the context of targeted antitumor therapy.
• To identify the most appropriate clinical methods for assessing EGFR expression and its variability in different tissues and tumor types.

Main Methods:

• Review of established detection techniques for HER2 overexpression: immunohistochemistry (protein) and in situ fluorescent hybridization (DNA).
• Analysis of diagnostic challenges associated with EGFR activation, including amplification, mutation, and enhanced transcription.
• Evaluation of immunohistochemistry as a primary clinical assay for EGFR, emphasizing the need for standardized assays and scoring systems.

Main Results:

• Well-established methods exist for HER2 overexpression detection, with no single technique demonstrating clear superiority.
• EGFR detection presents technical challenges due to diverse activation mechanisms; immunohistochemistry is deemed most suitable for clinical application.
• EGFR expression is notably high in normal tissues like oral mucosae and variable in tumors, with peak levels observed in head and neck epithelial tumors and dysplasia.

Conclusions:

• Standardization of assays and scoring is essential for reliable clinical use of EGFR testing.
• EGFR testing is a prerequisite for initiating targeted treatment in relevant malignancies.
• Future research should explore functional and dynamic evaluation of EGFR and downstream proteins for patient monitoring during therapy.