Vast scope of raman spectroscopy in oral cancers and head & neck regions: A review

Abstract

Higher rates of local recurrences and second primaries, ascribable to field cancerization, are known problems in oral cancers. The present review explored utility of identification of potential recurrences by Raman spectroscopy, which has been shown to identify oral precancers, cancers, and field cancerization in humans and micro-sized mechanical irritation-induced tumours in animals. There is an urgent need for improved techniques for disease detection. The focus here, in vivo Raman spectroscopy (RS), measures inelastic light scattering with the vibrational and rotational modes of molecular bonds in cells/tissue. The Raman ‘signature’ can be used to assess physiological and/or altered pathological statuses. This information can supplement existing diagnostic techniques for screening and diagnosis, in interventional guidance for identifying disease margins, and in monitoring treatment responses. Using fiberoptic-based light delivery and collection, RS is performed on accessible tissue surfaces, either on the skin, in hollow organs or intraoperatively. The strength of RS lies in the high biochemical information content of the spectra, that show an array of narrow peaks associated with specific chemical bonds. This results in high sensitivity and specificity, e.g., to distinguish malignant/premalignant from normal tissues. An issue with Raman signal is that it is often weak, limiting clinical use to point-by-point measurements. Recent advances in instrumentation and spectral analysis have improved the feasibility of RS, so that it is now being investigated with increased success in cancer types, locations and for non-oncological conditions. This review covers recent advances and continuing challenges, with emphasis on clinical translation.