PCDHGB7 (protocadherin gamma subfamily B, 7) is a calcium-dependent cell-adhesion protein involved in establishing and maintaining neuronal connections [UniProt]. While its primary neurobiological function remains characterized, PCDHGB7 has emerged as a significant epigenetic biomarker across multiple cancer types. In lung cancer, PCDHGB7 expression is downregulated and correlates with poor prognosis; notably, plasma PCDHGB7 methylation and protein levels predict immunotherapy response in non-small cell lung cancer 1. In breast cancer, PCDHGB7 promoter hypermethylation occurs frequently and serves as a diagnostic biomarker with high sensitivity and specificity 23. Functionally, PCDHGB7 increases chemosensitivity to carboplatin in triple-negative breast cancer by negatively regulating HSPA9, thereby promoting P53 translocation and caspase-3-mediated apoptosis 4. PCDHGB7 hypermethylation appears as a cancer-universal methylation marker in cell-free DNA of malignant body fluids 5 and is particularly valuable in cervical cancer screening, where PCDHGB7-based methylation detection effectively triages high-risk HPV-positive women with superior sensitivity and specificity compared to cytology 67. These findings position PCDHGB7 as a multi-functional tumor suppressor with dual roles in chemosensitivity and immunological regulation.