Quantifying HER-2 for Precision Oncology: The Role of Optical Biosensors.

The ability to measure the Human Epidermal Growth Factor Receptor 2 (HER-2), a biomarker associated with aggressive breast cancer and other malignancies, is vital to both providing an accurate diagnosis and tailoring individualized therapeutic management of patients. Although traditional approaches to diagnose HER-2 through laboratory testing using immunohistochemical techniques are established methods, they may be slow, semi-quantitative, and dependent on centralized laboratory facilities. This review first provides a concise overview of the biomarker HER-2 and its role in cancer, then proceeds to review recent advances in optical biosensing platforms designed for the sensitive and specific detection of HER-2. We describe how various optical transducers, including fluorescence, surface plasmon resonance (SPR), and colorimetric assays, are being used for quantification of HER-2 in clinical and experimental settings. We also highlight emerging point-of-care (POC) devices that utilize optical technologies for rapid, decentralized HER-2 measurement. In conclusion, this review discusses current challenges associated with the clinical translation of optical biosensors, including standardization, large-scale validation, and regulatory implementation, while also highlighting future directions involving nanotechnology integration, liquid biopsy strategies, and AI-assisted diagnostic systems for precision oncology.