Could Raman spectroscopy investigate the changes of cell oxidative stress status in thyroid diseases? A pilot study on cytological samples

The incidence of thyroid nodules is rapidly increasing worldwide. Raman spectroscopy (RS) is a powerful label-free and non-invasive technique, successfully used for early stage diagnosis. Here, RS is proposed as a tool to investigate the thyroid disease, including neoplasms, through the study of cell oxidative stress (OS), which represents one of the main cancer risk factors. In this study, we enrolled 28 patients, submitted to a first and second thyroid fine needle aspiration (FNA) during follow up. The cytological samples were studied by RS and morphological examination. Typical Raman spectra of thyroid cytological samples are reported and the contribution of oxidized and reduced cytochrome b and c and carotenoids are discussed. On the basis of the evolution of the Raman features over the time lapse between the two FNAs, the 28 patients have been classified into 4 different categories and the most representative case for each category is reported and discussed in detail. For each category, the different Raman intensity ratio between oxidized and reduced cytochromes b and c is reported and associated to different cell OS status, along with the presence of carotenoids. Overall, our results support a correlation among changes in oxidative stress, carotenoids uptake and thyroid diseases, which could inspire new fundamental research on biomarkers and signaling pathways involved in thyroid OS.