Quantitative terahertz dielectric analysis of paraffin-embedded tumors: correlation between cancer biomarkers PD-L1/Ki-67 and permittivity in lung cancer.

Terahertz technology has demonstrated significant potential for biomedical applications, particularly in tumor identification. Investigating the fundamental principles of terahertz-based tissue discrimination provides crucial theoretical foundations for developing THz imaging diagnostics and pathological analysis platforms. Current technical limitations, including constrained dynamic range and insufficient detection sensitivity, have hindered comprehensive characterization of tumor dielectric properties, particularly regarding statistically significant patterns and their pathological correlations. This study implemented a solid-state electronic terahertz system with multi-band stitching technology, achieving sensitive dielectric characterization across 0.11-1.1 THz. A total of 39 paired cancer and normal tissue samples from five organs (lung, kidney, colon, stomach, and breast) and two histological subtypes (adenocarcinoma and squamous carcinoma) were analyzed. Paraffin embedding was utilized to eliminate free water interference and improve detection sensitivity to intrinsic tissue properties, particularly specific protein content. Macroscopic statistical analysis revealed that cancer tissues exhibited consistently higher complex permittivity values compared to matched normal tissues, with a mean elevation of 0.135 and reduced data dispersion. Preliminary findings from in-depth microscopic pathological evaluation of nine lung cancer specimens revealed distinct correlation patterns: PD-L1 expression showed an exponential relationship while Ki-67 exhibited linear proportionality with tumor-normal permittivity differences in the real component. Combined with ultrastructural characterization, these dielectric disparities are attributed to tumor-induced changes in cellular density and overexpression of specific proteins. This work preliminarily establishes a quantitative association between terahertz dielectric responses and oncological biomarkers in lung cancer, providing important experimental evidence for advancing THz-based tumor analysis and diagnostic protocol development.