Portable SERS for salivary-based detection of oral pre-malignant lesions and carcinomas: a step toward clinical...

The rising incidence of oral cancer has emerged as a serious menace to our civilization. Modern dietary habits, lack of awareness, and delays in early detection are major contributing factors to the global spread of this issue. This work reports the promising findings for diagnostic accuracy of oral cancer in pre-malignant stages by analyzing surface enhanced Raman spectroscopy (SERS) profiles of different stages of oral cancer combined with multivariate analysis. Using 99 clinical samples from which 39 samples were from malignant stage, 28 from pre-malignant and 32 from healthy controls, SERS analysis was carried out by employing label-free silver nanorods as SERS substrates. The SERS spectra of malignant and pre-malignant samples manifest distinct peaks associated with varying concentrations of inorganic metabolites and proteins. Primarily, the elevated level of thiocyanate dominates the SERS spectra in malignant samples while antioxidants like uric acid, xanthine and hypoxanthine's are the key elements in the pre-malignant samples. A ratio-metric analysis of 2130 and 1435 cm^-1 peak revealed that the pre-malignant lesions consistently lie between 2 and 3, whereas malignant samples have ratio greater than 3 due to higher intensity of thiocyanate peak. The multivariate analysis successfully separates between oral cancer positive and negative samples with a sensitivity and specificity of 93.5 and 92.7 % respectively. This study presents promising results for the early detection of oral cancer, which could assist clinicians in saving lives.