Integrated triplex LFIA platform for decentralized molecular subtyping of breast cancer

Breast cancer is the most frequently diagnosed malignancy among women worldwide, with over 2.3 million new cases annually. Effective treatment relies on precise molecular subtyping, which stratifies tumors into categories such as Luminal A, Luminal B, HER2-enriched, and triple-negative breast cancer based on progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor 2 (HER2) expression. Despite its critical importance, subtyping remains largely inaccessible in low- and middle-income countries (LMICs) due to resource limitations, including the high cost and complexity of conventional diagnostic methods. Here, we present a rapid, portable, and cost-effective diagnostic platform that simultaneously quantifies PR, ER, and HER2 with high sensitivity and specificity. The system integrates a modular multiplex LFIA architecture, an incubation-enhanced reaction zone, and europium-based fluorescence detection with an automated, field-deployable imaging reader. These combined engineering features enable clinically relevant detection limits of 32 pM for PR, 76 pM for ER, and 25 pM for HER2, with cross-reactivity below 5%. Validation against enzyme-linked immunosorbent assay (ELISA) revealed strong correlation (R ² > 0.95) across subtype-representative biomarker mixtures. Together, this integrated approach has the potential to enhance breast cancer diagnosis and management by addressing critical barriers to timely and accurate subtyping, providing a practical tool to support earlier intervention, expand access to personalized treatment, and improve patient outcomes in resource-limited settings.