ATR FTIR spectroscopy shows high accuracy in breast tissue classification

Background and objectives

Histopathology is the gold standard in cancer diagnosis. However, attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy has shown diagnostic potential in other settings. Therefore, this study aimed to investigate the sensitivity and specificity of the ATR-FTIR spectroscopy in evaluating breast lesions.

Methods

This study was conducted on formalin-fixed, paraffin-embedded biopsy blocks received at Ladoke Akintola University of Technology Teaching Hospital between 2022 and 2023. The blocks were categorized into 10 normal (from benign breast tissue), 15 benign, and 31 malignant samples. Tissue sections of 15 µm were obtained during block trimming and floated onto FTIR slides. An additional 4 µm tissue sections were stained with hematoxylin and eosin for tumor diagnosis and to identify suitable areas on the FTIR slide. Spectrometer readings were taken within the range of 4000–600 cm⁻¹, 32 scans, and 16 cm⁻¹ resolution, using the average of 10 preprocessed spectra per slide. Biomarkers were calculated by ratioing peak intensities for A1632/A1543, A1632/A2922, A1632/A1080, A1080/A1543, A1237/A1080, and A1043/A1543, which represent protein, diagnostic marker, cytoplasm-nucleus ratio, carcinogenesis marker, phosphate, and glycogen, respectively. The receiver operating characteristic curve was used to determine sensitivity, specificity, and the area under the curve (AUC).

Results

The AUC analysis showed that cytoplasm-nucleus ratio values of 0.99 and 0.95 effectively distinguished normal from malignant tissue, and benign from malignant tissue, respectively (p < 0.0001). Additionally, protein marker (AUC = 0.73), diagnostic marker (AUC = 0.85), and cytoplasm-nucleus ratio marker (AUC = 0.94) were able to discriminate normal from benign tissue. Overall, the receiver operating characteristic analysis showed 100% sensitivity and specificity ranging from 54% to 87%. Glycogen (AUC = 1.00) exhibited 100% sensitivity in discriminating fibroadenoma from fibrocystic changes.

Conclusions

The study examines the efficacy of ATR-FTIR spectroscopy in distinguishing between normal and abnormal breast tissues using specific peak ratios as biomarkers. The research highlights that certain biomarkers, particularly the nucleocytoplasmic marker, demonstrate remarkable diagnostic accuracy, achieving an AUC ranging from 0.9 to 1.0, with a sensitivity of 100% in differentiating normal, benign, and cancerous tissues. Glycogen is identified as the most effective discriminator between fibrocystic changes and fibroadenomas, also showing perfect sensitivity and specificity. However, there is a need for future research with larger sample sizes to validate these findings.