Discriminant analysis of autofluorescence spectra for classification of oral lesions in vivo

Noninvasive Technique for the Screening and Diagnosis of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common types of malignancy. Squamous cell carcinoma is the second-most prevalent type of cutaneous malignancy after basal cell carcinoma. Biopsy followed by histopathological assessment is the primary basis for assessing squamous cell carcinoma, but nowadays optical non-invasive screening modalities are gaining more importance. There has been an emphasis on implementing relatively quick, affordable, and non-invasive screening methodologies because of various limitations associated with conventional screening techniques, including the encroaching characteristic of the biopsy technique, and the increased price value for treatment. Liquid biopsy, optical detection systems, oral brush cytology, and microfluidic detection, are a few examples of these, each of which has advantages and disadvantages of their own. Dermoscopy is one of the fundamental non-invasive screening techniques used for the examination of cutaneous lesions in clinical practice. Optical coherence tomography and high-frequency ultrasound are considered to be beneficial, particularly for assessing the dimensions of tumors before surgery. The primary site of the lesions, tumor diameter, and the state of the operative borders are some factors that can influence prognosis.

Comparative study of in-vitro autofluorescence of normal versus non-melanoma-skin-cancer cells at different excitation wavelengths

In this experimental study the autofluorescence of squamous carcinoma cells, stimulated by 6 different excitation wavelengths in the range 280-533 nm, has been compared with the autofluorescence of normal control keratinocytes. Skin cells were cultivated in vitro, to isolate their characteristic autofluorescence form the more complex one that would be originated by the complete skin tissue. Autofluorescence spectra in the visible range were complemented by absorption measurements. It was observed that the control cells showed characteristic emission (and absorption) structures due to typical endogenous chromophores [FAD and NAD(P)H, lipo-pigments, porphyrins], that were severely dumped in pathological cells. The autofluorescence spectra were then elaborated by multivariate analysis: after a first exploratory data analysis by means of Principal Component Analysis, the whole dataset was used to develop classification models using partial least squares-discriminant analysis, to differentiate between normal and pathological cells. This permitted us to identify the most suitable fluorescence spectral interval, in the 550-670 nm range, to discriminate between normal and pathological behavior, independently on the excitation wavelength.

Autofluorescence spectroscopy and multivariate analysis for predicting the induced damages to other organs due to liver fibrosis

When our liver does not work well, it can induce damage to other organs causing their dysfunction. With this background, we aim to study the effect of liver fibrosis on other organs such as heart, lungs, kidney and spleen by assessing the variations in the inherent emission property of the tissue, using fluorescence spectroscopy. Fluorescence emission spectra from excised organs of liver fibrosis induced rats were collected at excitation wavelengths 320 and 410 nm. Optical redox ratio derived from the spectral data supported by multivariate statistical analysis, principal component analysis followed by linear discriminant analysis (PCA-LDA) distinguished between control and fibrosis induced groups. The two different excitation wavelength provided variations in the endogenous flurophores collagen, nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD), lipopigments and porphyrins. Additionally, evaluation of redox ratio provided variations in tissue metabolic activity of different organs. The PCA-LDA modelling yielded a sensitivity of 85 to 97% and specificity of 80 to 96% on 320 nm excitation and a sensitivity of 72 to 100% and specificity of 59 to 100% on 410 nm excitation. Fluorescence emission spectral study along with multivariate analysis paved way to identify the biochemical alterations caused to other organs due to the development of liver fibrosis, which could lead to their damage and dysfunction.

Identification of oral precancerous and cancerous tissue by swept source optical coherence tomography

BACKGROUND AND OBJECTIVES

Distinguishing cancer from precancerous lesions is critical and challenging in oral medicine. As a noninvasive method, optical coherence tomography (OCT) has the advantages of real-time, in vivo, and large-depth imaging. Texture information hidden in OCT images can provide an important auxiliary effect for improving diagnostic accuracy. The aim of this study is to explore a reliable and accurate OCT-based method for the screening and diagnosis of human oral diseases, especially oral cancer.

MATERIALS AND METHODS

Fresh ex vivo oral tissues including normal mucosa, leukoplakia with epithelial hyperplasia (LEH), and oral squamous cell carcinoma (OSCC) were imaged intraoperatively by a homemade OCT system, and 58 texture features were extracted to create computational models of these tissues. A principal component analysis algorithm was employed to optimize the combination of texture feature vectors. The identification based on artificial neural network (ANN) was proposed and the sensitivity/specificity was calculated statistically to evaluate the classification performance.

RESULTS

A total of 71 sites of three types of oral tissues were measured, and 5176 OCT images of three types of oral tissues were used in this study. The superior classification result based on ANN was obtained with an average accuracy of 98.17%. The sensitivity and specificity of normal mucosa, LEH, and OSCC are 98.17% / 98.38%, 93.81% / 98.54%, and 98.11% / 99.04%, respectively.

CONCLUSION

It is demonstrated from the high accuracies, sensitivities, and specificities that texture-based analysis can be used to identify oral precancerous and cancerous tissue in OCT images, and it has the potential to help surgeons in diseases screening and diagnosis effectively.

Infrared Microspectroscopy With Multivariate Analysis to Differentiate Oral Hyperplasia From Squamous Cell Carcinoma: A Proof of Concept for Early Diagnosis

BACKGROUND AND OBJECTIVES

Despite having numerous advances in therapeutics, mortality and morbidity due to oral cancer incidence are still very high. Early detection can improve the chances of survival in most patients. However, diagnosis at early stages can be challenging as premalignant conditions are usually asymptomatic. Currently, histological assessment remains the gold standard for diagnosis. Early diagnosis poses challenges to pathologists due to less severe morphological changes associated with early stages. Therefore, a fast and robust method of detection based on molecular changes is needed for early diagnosis. © 2021 Wiley Periodicals LLC.

STUDY DESIGN/MATERIAL AND METHODS

In the present study, Fourier transform infrared (FTIR) spectroscopic imaging has been used to differentiate early-stage oral hyperplasia from adjacent normal (AN) and oral squamous cell carcinoma (OSCC). Hyperplasia is often considered as an initial event in the pathogenesis of oral cancer and OSCC is the most common advanced stage of malignancy. Differentiating normal versus hyperplasia and hyperplasia versus OSCC can remain quite challenging on occasion using conventional staining as the histological assessment is based on morphological changes.

RESULTS

Unsupervised hierarchical cluster analysis (UHCA) has been performed on FTIR images of multiple tissues together that provided some degree of classification among tissue groups. The AN epithelium clustered distinctively using UHCA from both hyperplasia and grades 1 and 2 of OSCC. An increase in the content of DNA, denaturation of protein, and altered lipid structures were more clearly elucidated with spectral analysis.

CONCLUSION

This study demonstrates a simple strategy to differentiate early-stage oral hyperplasia from AN and OSCC using UHCA. This study also proposes a future alternative method where FTIR imaging can be used as a diagnostic tool for cancer at early stages.

Differences in Spectroscopic Properties of Saliva Taken From Normal Subjects and Oral Cancer Patients: Comparison Studies

Oral cancer disease is among the most common cancers in the world and are associated with mortality and morbidity. The characterization of saliva samples may help to distinguish patients with oral cancer disease from normal subjects. To characterize spectra of saliva samples from normal subjects and oral cancer patients by use of fluorescence, absorption, and 1H-NMR spectroscopy. Whole unstimulated saliva samples were collected from patients with oral cancer disease and normal subjects. The saliva samples were analyzed by absorption, fluorescence and 1H-NMR spectroscopic techniques. The characteristic spectra of saliva samples from patients with oral cancer disease and normal subjects were compared. For fluorescence spectroscopic studies, six fluorophores were found in saliva samples. Autofluorescence emission spectra and synchronous spectra of saliva were different between normal subjects and oral cancer patients. For absorption spectroscopic studies, the typical absorption spectra of saliva samples from normal subjects and oral cancer patients were also different in absorption intensity, 1st and 2nd derivative of absorption spectra values. For 1H-NMR studies, nine metabolites and four metabolites were found in saliva samples taken from normal subjects and oral cancer patients, respectively. The metabolic profiles of saliva samples from normal subjects and oral cancer patients were not similar. The characteristic spectra of saliva samples from normal subjects and oral cancer patients were found. These results showed differences in the spectra of saliva samples between both that groups. The spectra from each spectroscopic techniques could determine a candidate saliva biomarkers for distinguishing patients with oral cancer disease from normal subjects.

Recent advances in point-of-care diagnostics for oral cancer

Early-stage diagnosis is a crucial step in reducing the mortality rate in oral cancer cases. Point-of-care (POC) devices for oral cancer diagnosis hold great future potential in improving the survival rates as well as the quality of life of oral cancer patients. The conventional oral examination followed by needle biopsy and histopathological analysis have limited diagnostic accuracy. Besides, it involves patient discomfort and is not feasible in resource-limited settings. POC detection of biomarkers and diagnostic adjuncts has emerged as non- or minimally invasive tools for the diagnosis of oral cancer at an early stage. Various biosensors have been developed for the rapid detection of oral cancer biomarkers at the point-of-care. Several optical imaging methods have also been employed as adjuncts to detect alterations in oral tissue indicative of malignancy. This review summarizes the different POC platforms developed for the detection of oral cancer biomarkers, along with various POC imaging and cytological adjuncts that aid in oral cancer diagnosis, especially in low resource settings. Various immunosensors and nucleic acid biosensors developed to detect oral cancer biomarkers are summarized with examples. The different imaging methods used to detect oral tissue malignancy are also discussed herein. Additionally, the currently available commercial devices used as adjuncts in the POC detection of oral cancer are emphasized along with their characteristics. Finally, we discuss the limitations and challenges that persist in translating the developed POC techniques in the clinical settings for oral cancer diagnosis, along with future perspectives.

Optical diagnosis of oral lichen planus: A clinical study on the use of autofluorescence spectroscopy combined with multivariate analysis

Oral lichen planus (OLP) is a chronic mucocutaneous inflammatory condition of stratified squamous epithelia. OLP is a potentially malignant condition in oral mucosa. Patients with OLP have an increased risk of developing squamous cell carcinoma. Therefore an early and accurate diagnosis is necessary to avoid further damage to the oral mucosa. Biopsy followed by histopathological examination is the gold standard for the diagnosis of oral mucosal lesions including OLP. But this invasive procedure is traumatic and time consuming with limited statistical confidence level. Autofluorescence spectroscopy (AFS) has recently emerged as a potential tool to evaluate the biochemical changes associated with oral cavity disorders. In this study, we used AFS to differentiate the oral cavity tissue of 20 OLP patients from that of 16 normal volunteers. Spectra from oral mucosa were acquired at 280, 320 and 410 nm excitation wavelengths which correspond to the excitation energy of major endogenous fluorophores. Normalized spectral data at 320 nm excitation showed significant increase in the intensity of collagen peak for OLP. Optical redox ratio and total hemoglobin concentration estimated from the spectral data revealed significant increase and decrease respectively in OLP and normal patients. Principal component analysis followed by linear discriminant analysis (PCA-LDA) provided sensitivity and specificity of 71 and 80%, 80 and 90%, and 72 and 75% respectively for 280, 320 and 410 nm excited spectral datasets. Meanwhile, partial least square discriminant analysis (PLS-DA) provided sensitivity and specificity of 69 and 77%, 78 and 91% and 73 and 78.13% respectively for 280, 320 and 410 nm excited spectral datasets. From the results, it is concluded that AFS is an efficient tool for the non invasive diagnosis of OLP, with 320 nm light identified as the best wavelength for excitation.

Use of autofluorescence and fluorescent probes as a potential diagnostic tool for oral cancer: A systematic review

INTRODUCTION

The prognosis of patients with Oral squamous cell carcinoma (OSCC) are directly related to the stage of development of the tumor at the time of diagnosis, but it is estimated an average delay in diagnosis of 2-5 months. New non-invasive techniques for the early diagnosis of OSCC are being developed, such as methodologies to detect spectral changes of tumor cells. We conducted a systematic review to analyze the potential use of autofluorescence and/or fluorescent probes for OSCC diagnosis.

MATERIAL AND METHODS

Four databases (PubMed, Scopus, Embase and Web of Science) were used as research sources. Protocol was registered with PROSPERO. It was included studies that evaluated tissue autofluorescence and/or used fluorescent probes as a method of diagnosing and/or treatment of oral cancer in humans.

RESULTS

Forty-five studies were selected for this systematic review, of which 28 dealt only with autofluorescence, 18 on fluorescent probes and 1 evaluated both methods. The VELscope® was the most used device for autofluorescence, exhibiting sensitivity (33%-100%) and specificity (12%-88.6%). 5-Aminolevulinic acid (5-ALA) was the most used fluorescent probe, exhibiting high sensitivity (90%-100%) and specificity (51.3%-96%). Hypericin, rhodamine 6 G, rhodamine 610, porphyrin and γ-glutamyl hydroxymethyl rhodamine green have also been reported.

CONCLUSION

Thus, the autofluorescence and fluorescent probes can provide an accurate diagnosis of oral cancer, assisting the dentist during daily clinical activity, but it is not yet possible to suggest that this method may replace histopathological examination.

Histopathological determinants of autofluorescence patterns in oral carcinoma

Biological tissues (including oral mucosa) can absorb and re-emit specific light wavelengths, detectable through spectrophotometric devices. Such a phenomenon is known as "autofluorescence" (AF). Several devices evaluating tissue AF have been developed and commercialized in the last two decades. Among these, the VELscope® system has been proposed as a visual diagnostic aid for potentially malignant disorders and malignant lesions of the oral mucosa. In the present pilot study, we investigated which are the main histopathological features possibly related to variations in AF patterns in a set of 20 oral squamous cell verrucous carcinoma. Among all the histological features investigated, only the mean width of keratin was significantly different between hypofluorescent and hyperfluorescent carcinomas. The results of the present study demonstrate that AF features of oral malignant lesions are significantly associated with the width of their keratin layer.

Recent Advances and the Potential for Clinical Use of Autofluorescence Detection of Extra-Ophthalmic Tissues

The autofluorescence (AF) characteristics of endogenous fluorophores allow the label-free assessment and visualization of cells and tissues of the human body. While AF imaging (AFI) is well-established in ophthalmology, its clinical applications are steadily expanding to other disciplines. This review summarizes clinical advances of AF techniques published during the past decade. A systematic search of the MEDLINE database and Cochrane Library databases was performed to identify clinical AF studies in extra-ophthalmic tissues. In total, 1097 articles were identified, of which 113 from internal medicine, surgery, oral medicine, and dermatology were reviewed. While comparable technological standards exist in diabetology and cardiology, in all other disciplines, comparability between studies is limited due to the number of differing AF techniques and non-standardized imaging and data analysis. Clear evidence was found for skin AF as a surrogate for blood glucose homeostasis or cardiovascular risk grading. In thyroid surgery, foremost, less experienced surgeons may benefit from the AF-guided intraoperative separation of parathyroid from thyroid tissue. There is a growing interest in AF techniques in clinical disciplines, and promising advances have been made during the past decade. However, further research and development are mandatory to overcome the existing limitations and to maximize the clinical benefits.

Which are the main fluorophores in skin and oral mucosa? A review with emphasis on clinical applications of tissue autofluorescence

OBJECTIVES

The present review provides information about which molecules appear to be the main fluorophores in skin and oral mucosa, together with their clinical applications.

DESIGN

The MEDLINE database was searched, using "oral mucosa AND fluorophores", "skin AND fluorophores", "epidermal AND fluorophores", "dermal AND fluorophores" and "cutaneous AND fluorophores" as entry terms. We searched the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The level of evidence in the studies was assessed using the Classification of the Oxford Centre for Evidence-based Medicine (CEBM) Levels for Diagnosis.

RESULTS

Five papers and 17 were primarily focused on description of fluorophores in oral mucosa and skin Evidence exists that fluorophores of oral mucosa and skin are mainly proteins such as collagen, elastin, keratin and tryptophan. Other possible fluorophores identified are: porphyrins, advanced glycation end products, flavins, lipopigment, nicotinamide adenine dinucleotide, flavin adenine dinucleotide, pheomelanin, eumelanin and components of lipofuscin. Clinical applications of oral mucosal autofluorescence (AF) are related to management of malignant and potentially malignant lesions. In the skin, AF has been used for acne assessment, diagnosis of sweat-gland pathologies, glycemic control and management of malignant lesions and as a marker for skin aging.

CONCLUSION

Fluorophores stimulated through AF devices are implied in different physiologic and pathologic processes. AF seems to be useful for several clinical applications, especially in skin department. Because most of the studies show a low level of evidence, further studies are necessary in such a promising and fascinating field.

Techniques for early diagnosis of oral squamous cell carcinoma: Systematic review

Background and objectives

The diagnosis of early oral potentially malignant disorders (OPMD) and oral squamous cell carcinoma (OSCC) is of paramount clinical importance given the mortality rate of late stage disease. The aim of this study is to review the literature to assess the current situation and progress in this area.

Material and Methods

A search in Cochrane and PubMed (January 2006 to December 2013) has been used with the key words “squamous cell carcinoma”, “early diagnosis” “oral cavity”, “Potentially Malignant Disorders” y “premalignant lesions”. The inclusion criteria were the use of techniques for early diagnosis of OSCC and OPMD, 7 years aged articles and publications written in English, French or Spanish. The exclusion criteria were case reports and studies in other languages.

Results

Out of the 89 studies obtained initially from the search 60 articles were selected to be included in the systematic review: 1 metaanalysis, 17 systematic reviews, 35 prospective studies, 5 retrospective studies, 1 consensus and 1 semi-structured interviews.

Conclusions

The best diagnostic technique is that which we have sufficient experience and training. Definitely tissue biopsy and histopathological examination should remain the gold standard for oral cancer diagnose. In this systematic review it has not been found sufficient scientific evidence on the majority of proposed techniques for early diagnosis of OSCC, therefore more extensive and exhaustive studies are needed.

Key words: Squamous cell carcinoma, early diagnosis, oral cavity, potentially malignant disorders, premalignant lesions.

Systematic diagnosis of prostate cancer using an optical biopsy needle adjunct with fluorescence spectroscopy

Transrectal ultrasound guided prostate biopsies often fail to diagnose prostate cancer with 90% of cores reported as benign. Thus, it is desirable to target prostate cancer lesions while reducing the sampling of benign tissue. The concentrations of natural fluorophores in prostate tissue fluctuate with disease states. Hence, fluorescence spectroscopy could be used to quantify these fluctuations to identify prostate cancer. An optical biopsy needle with a light sensitive optical probe at the tip of the inner needle was developed to take prostate biopsies after measuring tissue fluorescence with a laboratory fluorometer. The optical probe consists of eight 100 μm fibers for tissue excitation and a single 200 μm fiber to capture fluorescence spectra. Random biopsy cores were taken from 20 surgically excised prostates after measuring fluorescence spectra of tissue between 295-550nm for several excitations between 280-350nm. Each biopsy core was histopathologically classified and correlated with corresponding spectra. Prostate biopsies were grouped into benign or malignant based on the histological findings. Out of 187 biopsy cores, 109 were benign and 78 were malignant. Partial least square analysis of tissue spectra was performed to identify diagnostically significant principal components as potential classifiers. A linear support vector machine and leave-one-out cross validation method was employed for tissue classification. Study results show 86% sensitivity, 87% specificity, 90% negative predictive value, and 83% positive predictive value for benign versus malignant prostate tissue classification. This study demonstrates potential clinical applications of fluorescence spectroscopy guided optical biopsy needle for prostate cancer diagnosis with the consequent improvement of patient care.

Optical diagnosis of the progression and reversal of CCl4-induced liver injury in rodent model using minimally invasive autofluorescence spectroscopy

Schematic representation of the degree of intoxicant-induced liver injury and regeneration and the minimally invasive analysis using autofluorescence spectral features.

Fluorescence spectroscopic characterization of salivary metabolites of oral cancer patients

A pilot study has been carried out using human saliva in differentiating the normal subjects from that of oral squamous cell carcinoma (OSCC) patients, using the autofluorescence spectroscopy at 405nm excitation. A markable difference in the spectral signatures between the saliva of normal subjects and that of oral cancer patients has been noticed. The possible reasons for the altered spectral signature may be due to the presence of endogenous porphyrin, NAD(P)H and FAD in the exfoliated cells from saliva. The elevated level of porphyrin in saliva of OSCC patients may be attributed to the disturbances in the amino acid degradation pathway and heme biosynthetic pathway, during the transformation of normal into malignant cells. The integrated area under the curve of fluorescence emission spectrum at 405nm excitation and also fluorescence excitation spectrum for 625nm emission were compared for the saliva of normal and oral cancer patients. The area under the curve for the emission spectrum provides 85.7% sensitivity and 93.3% specificity, where as the fluorescence excitation spectrum discriminates the same with 84.1% sensitivity and 93.2% specificity.

Comparative evaluation of the diagnostic performance of autofluorescence and diffuse reflectance in oral cancer detection: a clinical study

Autofluorescence (AF) and diffuse reflectance (DR) spectroscopic techniques have shown good diagnostic accuracies for noninvasive detection of oral cavity cancer. In the present study, AF and DR spectra recorded in vivo from the same set of sites in 65 patients were analyzed using Principal component analysis (PCA) and linear discriminant analysis (LDA). The effectiveness of these two techniques was assessed by comparison with gold standard and their discrimination efficiency was determined from the area under the receiver operator characteristic (AUC-ROC) curve. Analysis using a DR technique shows a higher AUC-ROC of 0.991 as against 0.987 for AF spectral data.

Habits with killer instincts: in vivo analysis on the severity of oral mucosal alterations using autofluorescence spectroscopy

Oral habits like chewing and smoking are main causes of oral cancer, which has a higher mortality rate than many other cancer forms. Currently, the long term survival rate of oral cancer is less than 50%, as a majority of cases are detected very late. The clinician's main challenge is to differentiate among a multitude of red, white, or ulcerated lesions. Hence, new noninvasive, reliable, and fast techniques for the discrimination of oral cavity disorders are to be developed. This study includes autofluorescence spectroscopic screening of normal volunteers with and without lifestyle oral habits and patients with oral submucous fibrosis (OSF). The spectra from different sites of habitués, non-habitués, and OSF patients were analyzed using the intensity ratio, redox ratio, and linear discriminant analysis (LDA). The spectral disparities among these groups are well demonstrated in the emission regions of collagen and Flavin adenine dinucleotide. We observed that LDA gives better efficiency of classification than the intensity ratio technique. Even the differentiation of habitués and non-habitués could be well established with LDA. The study concludes that the clinical application of autofluorescence spectroscopy along with LDA, yields spontaneous screening among individuals, facilitating better patient management for clinicians and better quality of life for patients.

Diffuse reflectance spectroscopy: diagnostic accuracy of a non-invasive screening technique for early detection of malignant changes in the oral cavity

BACKGROUND

Strong proof-of-principle for utilisation of diffuse reflectance spectroscopy, a non-invasive tool for early detection of malignant changes, has emerged recently. The potential of this technique in distinguishing normal tissue from hyperplastic and dysplastic tissues was explored.

METHODS

Diffuse reflectance (DR) spectra in the 400-700 nm region were obtained from the buccal mucosa of 96 patients and 34 healthy volunteers. The DR spectral data were compared against the gold standard biopsy and histopathology results. A principal-component analysis was performed for dimensional reduction in the normalised spectral data with linear discriminant analysis as the classifying technique. The receiver operator characteristic curve technique was employed for evaluating the performance of the diagnostic test.

RESULTS

DR spectral features for different lesions, such as normal/healthy, hyperplastic, dysplastic and squamous cell carcinoma (SCC), varied significantly according to the intensity of oxygenated haemoglobin absorption. While the classification based on discriminant scores provided an overall sensitivity of 98.5% and specificity of 96.0% for distinguishing SCC from dysplasia, they were 100.0% and 95.0%, respectively, for distinguishing dysplasia from hyperplasia. Similarly, the analysis yielded a sensitivity of 95.0% and specificity of 100.0% for distinguishing hyperplasia from healthy tissue. The areas under the receiver operator characteristic curves were 0.98 (95% CI 0.95 to 1.00) and 0.95 (95% CI 0.90 to 1.00) for distinguishing dysplasia from SCC and hyperplasia from dysplasia, respectively.

CONCLUSION

DR spectral data efficiently discriminate healthy tissue from oral malignant lesions. Diagnostic accuracies obtained in this study highlight the potential use of this method for routine clinical practice.

[Autofluorescence for the detection of potentially malignant and malignant lesions of the oral cavity lining]

INTRODUCTION

The sensitivity of visual examination for the diagnosis of oral cancers is estimated at 85% and its specificity at 97%. However, it is likely that numerous lesions remain undetected. The objective of this article was to review literature on the contribution of tissular autofluorescence to detect potentially malignant and malignant lesions of the oral cavity.

MATERIAL AND METHOD

The Medline database was consulted using the following keywords: fluorescence and cancer; autofluorescence and cancer; fluorescence and oral cancer; autofluorescence and oral cancer; Velscope(®) and oral cancer. Only original articles and clinical case reports on the oral cavity published in English since 1999 were considered.

RESULTS

Twenty-three publications were analyzed. Twelve studies concerned spectroscopy and 14 direct autofluorescence. The specificity of AF ranged between 75 and 100% in spectroscopy and between 39 and 100% in direct vision. The sensibility of the AF varied between 78 and 100% in spectroscopy and between 50 and 100% in direct vision.

DISCUSSION

The variability of results may be explained by selection bias. The main contribution of fluorescence is to highlight oral mucous membrane lesions and to help physicians to better locate them. The lack of AF specificity supports the contribution of histological examination which remains the reference examination for the diagnosis of potentially malignant lesions and cancers of the oral cavity.

Clinical grading of oral mucosa by curve-fitting of corrected autofluorescence using diffuse reflectance spectra

BACKGROUND

Laser-induced autofluorescence (LIAF) and diffuse reflectance (DR) were collectively used in this clinical study to improve early oral cancer diagnosis and tissue grading.

METHODS

LIAF and DR emission from oral mucosa were recorded on a fiber-optic spectrometer by illumination with a 404-nm diode laser and tungsten halogen lamp in 36 healthy volunteers and 40 lesions of 20 patients.

RESULTS

Absorption dips in LIAF spectra at 545 and 575 nm resulting from changes in oxygenated hemoglobin were corrected using DR spectra of the same site. These corrected spectra were curve-fitted using Gaussian spectral functions to determine constituent emission peaks and their relative contribution. The Gaussian peak intensity and area ratios F500/F635 and F500/F685 were found to be useful indicators of tissue transformation. The diagnostic capability of various ratios in differentiating healthy, hyperplastic, dysplastic, and squamous cell carcinomas (SCCs) were examined using discrimination scatterplots.

CONCLUSIONS

The LIAF/DR technique, in conjunction with curve-fitting, differentiates different grades of dysplasia and SCC in this clinical trial and proves its potential for early detection of oral cavity cancer and tissue grading.

Searching for metachronous tumours in patients with head and neck cancer: the ideal protocol!

PURPOSE OF REVIEW

As treatment changes in the management of head and neck cancer, patients are reportedly living longer; therefore, their death may be due to comorbidity, metastatic disease or the development of a metachronous second primary tumour (MSPT). This review describes recent developments in the identification of MSPTs of head and neck cancer, oesophagus and lung, and suggests/recommends an 'ideal surveillance protocol'.

RECENT FINDINGS

The rate of MSPT development ranges between 6 and 9% annually for life. Improved accuracy in the detection of mucosal asymptomatic premalignant and early cancer has been enhanced by incorporating fluorescence spectroscopy in addition to modern flexible endoscopic techniques in the outpatient setting. Newer imaging has replaced old techniques (chest radiograph, barium swallow, etc.) by using radiotracer PET-computed tomography to detect local tumour activity. Further advances are anticipated in optical diagnostics and the incorporation of radiopharmaceuticals with labelled antibodies to enhance PET imaging, thus making tumour identification more accurate. Genetic classification of head and neck cancer has already identified high-risk patient groups, thereby allowing expensive tumour screening techniques to be used selectively and specifically. Patients who continue to smoke and abuse alcohol must be helped and encouraged to quit.

SUMMARY

It is now possible to review traditional follow-up policy for treated head and neck cancer patients, to encourage the implementation of an evidence-based surveillance protocol, to identify only patients who are at high-risk of developing a MSPT, to incorporate modern targeted expensive tumour screening and to allow treatment of early cancer and effective treatment, thereby improving patients' quality of life and increasing survival.