In vivo Raman spectroscopy of oral buccal mucosa: a study on malignancy associated changes (MAC)/cancer field effects (CFE)

Abstract

Occurrence of metachronous and synchronous secondary tumors in oral cavities has been associated with poor prognosis and decreased 5-year disease-free survival rates. The origin of secondary tumors in the oral cavity has been primarily attributed to cancer field effects (CFE) or malignancy-associated changes (MAC) in uninvolved areas. Classification of normal, cancerous and pre-cancerous oral lesions by in vivo Raman spectroscopy (RS) has already been demonstrated. In the present study, MAC/CFE in oral buccal mucosa were explored. In vivo Raman spectra from 84 subjects (722 spectra) under five categories - cancer and contralateral normal (opposite side of tumor), healthy controls (no tobacco habit, no cancer), habitués healthy controls (tobacco habit, no cancer) and non-habitués contralateral normal (no tobacco habit with cancer) were acquired. Mean and difference spectra suggest that loss of lipids and additional features representing proteins and DNA are characteristics of all pathological conditions, with respect to healthy controls. Spectral data were analyzed by PC-LDA followed by leave-one-out cross-validation. Results suggest that Raman characteristics of mucosa of healthy controls are exclusive, while those of habitués healthy controls are similar to those of contralateral normal mucosa. It was observed that the cluster of non-habitués contralateral normal mucosa is different from habitués healthy controls, suggesting that malignancy associated changes can be identified and also indicating that transformation of uninvolved oral mucosa due to tobacco habit or malignancy is different. The findings of the study demonstrate the potential of RS in identifying early transformation changes in oral mucosa and the efficacy of this approach in oral cancer applications.

In vivosubsite classification and diagnosis of oral cancers using Raman spectroscopy

“…RS has also shown to detect age-related physiological conditions and even subtle cancer-¯eld e®ects (CFE). 25,26 However, these two studies undertaken in the present laboratory established the potential of RS for only buccal mucosa subsite. Additionally, two recent studies have also investigated possibility of surgical demarcation using tumor and normal biopsies.…”

“…25 This system consists of a diode laser (Process Instruments, USA) of 785 nm wavelength as the excitation source, a high e±ciency (HE) spectrograph with¯xed 950 gr/mm grating coupled with a CCD (Synapse). The instrument has no movable parts and the spectral resolution as speci¯ed by the manufacturer is 4 cm À1 .…”

“…These¯ndings corroborate our previous ex vivo and in vivo¯ndings. [19][20][21]25,26 The tentative assignments were made as per available literature. 45,46 3.2.…”

Developing fibre optic Raman probes for applications in clinical spectroscopy

“…13 Furthermore, Singh et al demonstrated malignancy associated changes in the buccal mucosa probed by Raman in at risk patient groups from tobacco exposure. 14 Although Raman has good chemical specificity, it is hindered by the low probability of an inelastic scattering event. From one million photons interacting with a molecule, there may only be one photon that is inelastically scattered.…”

Longitudinal Raman Spectroscopic Observation of Skin Biochemical Changes due to Chemotherapeutic Treatment for Breast Cancer in Small Animal Model

“…Since first finding of CFE from oral cancers in 1953 [1], studies related to CFE have been gradually increased [2,3]. While other techniques including microscopy, polymerase chain reaction (PCR), and immunohistochemistry were utilized to study CFE [3][4][5][6], Raman spectroscopy has been spotlighted as a useful tool since it has been shown that the spectroscopy can detect changes that are insensitive to histological evaluation implying that chemical changes are not local and proceed earlier than anatomical or physical changes [7][8][9]. Such studies proved the ability of Raman spectroscopy as a dominant candidate for a sensitive and minimally invasive optical biopsy tool.…”