Pilot study on the value of Raman spectroscopy in the entity assignment of salivary gland tumors

Abstract

Background The entity assignment of salivary gland tumors (SGT) based on histomorphology can be challenging. Raman spectroscopy has been applied to analyze differences in the molecular composition of tissues. The aim of this study was to evaluate the suitability of RS for entity assignment in SGT. Methods Raman data were collected in deparaffinized sections of pleomorphic adenomas (PA) and adenoid cystic carcinomas (ACC). Multivariate data and chemometric analysis were completed using the Unscrambler software. Results The Raman spectra detected in ACC samples were mostly assigned to nucleic acids, lipids, and amides. In a principal component-based linear discriminant analysis (LDA) 18 of 20 tumor samples were classified correctly. Conclusion In this proof of concept study, we show that a reliable SGT diagnosis based on LDA algorithm appears possible, despite variations in the entity-specific mean spectra. However, a standardized workflow for tissue sample preparation, measurement setup, and chemometric algorithms is essential to get reliable results.

The Impact of Tissue Preparation on Salivary Gland Tumors Investigated by Fourier-Transform Infrared Microspectroscopy

“…The considerable variety of benign and malignant SGTs becomes obvious by looking at the 2017 WHO Classification of Head and Neck Tumors, which differentiates between more than thirty different benign and malignant SGTs [ 2 ]. Unambiguous SGT classification and malignant behavior determination based on histomorphology alone can be challenging and, in some cases, impossible [ 3 ], which may complicate particularly a reliable intraoperative frozen section diagnosis.…”

“…The investigation of parotid SGTs is rare due to a lack of sample availability and quality. Some studies focused on the differentiation of SGT entities or their protein and lipid composition determination by other spectroscopic methods [ 3 , 22 , 23 ], but so far only few groups used FTIR spectroscopy for head and neck tumors in general [ 24 ].…”

Differentiation of Salivary Gland and Salivary Gland Tumor Tissue via Raman Imaging Combined with Multivariate Data Analysis

“…Further studies focused on identifying differences in lipid composition and changes in secondary protein structure between cancerous and non-cancerous salivary gland tissue using Raman imaging [ 38 ]. Our group just recently published a study employing Raman spectroscopy and PCA analysis to enable a differentiation between benign pleomorphic adenoma and low-malignant adenoid cystic carcinomas [ 39 ]. Although primary efforts in differentiating SGTs were achieved, no study on deploying spectral differences has been published yet to implement a Raman-MVA model as diagnostic adjunct and review its functionality.…”