Raman spectroscopy and cytopathology of oral exfoliated cells for oral cancer diagnosis

Abstract

For oral cancers, screening and monitoring of high-risk populations can aid in early diagnosis and improve overall outcomes. Of the new methods, approaches based on exfoliative cytology are more practical for mass screening and monitoring of high-risk populations. Raman spectroscopy and exfoliative cytology for cervical cancers has shown promise in differentiating normal and abnormal samples. In this study, feasibility of Raman oral exfoliative cytology along with cytopathology for oral cancer diagnosis was evaluated on 70 specimens. Exfoliated cells were obtained from 15 healthy volunteers (HV), 15 healthy tobacco users (HT), and 20 contralateral or disease control (DC) and 20 tumor (T) sites of oral-cancer patients. Pap staining was carried out post Raman spectral acquisition. Spectral findings demonstrate that with increase in severity of pathology from HV to T, higher DNA and changes in secondary structure of proteins were encountered. Owing to heterogeneity in cellular samples, two different approaches-point-spectra and patient-wise were evaluated for data analysis. PCA and PC-LDA using both approaches indicate that HV and HT are distinct from cancer groups DC and T.Misclassifications were also observed between HT and DC. These findings also correlate with cytopathological findings. Less misclassifications and higher classification efficiency was observed for patient-wise approach. Large-scale validation study needs to be undertaken for evaluating utility of Raman oral exfoliative cytology for screening of oral cancers using patientwise approach.The incidence of oral cancer worldwide is around 300000 new cases every year 1 . Tobacco abuse (smoking and smokeless) is the most common etiological factor for oral cancer 2 . The overall 5year survival rate of around 50% is mainly attributed to delayed diagnosis and recurrence. These rates are less than occult cancers like breast, colorectal, cervix 3 . Early detection of oral cancer and its curable precursors remains the best way to ensure patient survival and improved quality of life 4, 5 . South Asian countries like India are major contributors to the global cancer burden, due to rampant tobacco habits. In fact, it is estimated that over 90% of the global smokeless tobacco burden is in South Asia-around 100 million people use smokeless tobacco in India and Pakistan alone 6, 7 . Due to a known dose-response relationship between tobacco consumption and development of oral cancer, chronic tobacco abusers are at high risk for development of oral cancer 8 . Thus, screening and monitoring of these high-risk populations, along with the general population is crucial.The current standard screening procedure for oral cancers is visual inspection followed by biopsy and histopathology of suspicious lesions. These currently employed methods have shown limited potential in detecting precancerous or early cancerous lesions 9 . In fact, visual examination was useful as a method of screening for oral cancer only in high risk cases like chronic smokers or alcoholics 10 . The susp...

Raman exfoliative cytology for prognosis prediction in oral cancers: A proof of concept study

“…The clinical significance of contralateral normal misclassifications with tumor in predicting recurrences in oral cancer patients in vivo was recently demonstrated by Malik et al . In the present study, we have investigated the feasibility of detecting recurrences through Raman exfoliative cytology, after successfully differentiating normal, premalignant and malignant cells . Exfoliative cytology is associated with advantages such as minimally‐invasive sampling, possibility of multiple sampling and sample transportation to a centralized facility for analysis, and is a more practical approach for patient monitoring in low‐resource settings.…”

“…Thereafter, cells were manually exfoliated from representative areas in the oral cavity of participants, selected by the physician. The procedure for exfoliated cell collection and processing has been described previously . Briefly, cells were collected using Cytobrush (Himedia, India) in normal saline, transported in ice, processed using RBC lysis protocol and subjected to cell counting.…”

“…The cells are stained based on the degree of maturation and keratin content. Post spectral acquisition, cell pellet was smeared on glass slide, fixed in 95% ethanol, and Pap stained using protocol described elsewhere . The slides were read by a certified pathologist.…”

The role of exfoliative cytology and molecular biology in oral potentially malignant disorders

“…[41,42] Application of Raman spectroscopy in early detection of oral cancer using exfoliative cytology has also been recently reported. [43]…”

Raman Spectroscopy in Colorectal Cancer Diagnostics: Comparison of PCA-LDA and PLS-DA Models

“…This technology investigates molecular vibrations that can be used for functional group identification and compositional analysis. Extensive research has demonstrated that Raman spectroscopy can support gold-standard techniques and substantially improve clinical diagnostics [5][6][7][8][9]. Raman measurements on biopsies can help pathologists identify the tumor margins in a fast and precise way.…”