Detection of squamous cell carcinomas and pre-cancerous lesions in the oral cavity by quantification of 5-aminolevulinic acid induced fluorescence endoscopic images

Photodynamic Diagnosis Using 5-Aminolevulinic Acid with a Novel Compact System and Chromaticity Analysis for the Detection of Oral Cancer and High-Risk Potentially Malignant Oral Disorders

Detecting early-stage oral cancer and precancerous lesions are critical to improving patient prognosis and quality of life after treatment. Photodynamic diagnosis using 5-aminolevulinic acid enables the detection of malignant lesions. This study aimed to improve the diagnostic accuracy of photodynamic diagnosis using an objective chromaticity analysis of fluorescence emitted from oral lesions. Sixty-seven patients with clinically suspicious oral cavity lesions underwent photodynamic diagnosis after topical application of 5-aminolevulinic acid solution, followed by imaging and histological evaluation of the lesions. Chromaticity red and green values were measured from the fluorescence images on the lesion, and the red-to-green ratio was calculated. The photodynamic diagnosis allowed for the visualization of oral cancer and high-risk dysplasia as red fluorescence. Compared to low-risk dysplasia and benign lesions, oral cancer and high-risk dysplasia areas had a significantly higher red value and red-to-green ratio. After setting the cutoff value, sensitivity and specificity were 83.3–88.7% and 83.3–83.9%, respectively, when discriminating between oral cancer or high-risk dysplasia and low-risk dysplasia or benign lesions. Photodynamic diagnosis combined with chromaticity analysis may be a valuable diagnostic tool for detecting oral lesions, with a high likelihood of malignant transformation.

Diagnostic accuracy of clinical visualization and light-based tests in precancerous and cancerous lesions of the oral cavity and oropharynx: a systematic review and meta-analysis

OBJECTIVE

Evaluate and compare the performance of autofluorescence, chemiluminescence, and clinical visual examination in the detection of oral potentially malignant disorders (OPMD), oral cancer (OC), and oropharyngeal cancer (OPC).

MATERIALS AND METHODS

A systematic review with meta-analysis based on diagnostic test studies. A literature search was carried out in the MEDLINE and EMBASE databases through August 30, 2020. For this review, the quality assessment tool of diagnostic precision studies (QUADAS-2) was used. Hierarchical regression models were used to estimate pooled diagnostic precision values in a random effects model.

RESULTS

A total of 40 studies were identified for this review according to each test evaluated: 5.562 samples for autofluorescence, 1.353 samples for chemiluminescence, and 1.892 samples for clinical examination. The summary measures sensitivity and specificity of the clinical examination were 63% and 78%, respectively, AUC = 0.78 95% CI (0.74-0.81). In the autofluorescence test, these were 86% and 72%, respectively, AUC = 0.86 95% CI (0.83-0.89); and the chemiluminescent test were 67% and 48%, respectively, AUC = 0.59 95% CI (0.54-0.63) CONCLUSIONS: Autofluorescence devices displayed superior accuracy levels in the identification of premalignant lesions and early neoplastic changes compared to clinical examination and chemiluminescent test. Overall, biopsy remains the gold standard for the definitive diagnosis of OPMD, OC, and OPC.

CLINICAL RELEVANCE

Light-based clinical methods such as autofluorescence and chemiluminescence techniques have been used in clinical diagnosis for the differentiation of OPMD and malignant and benign lesions; although detailed visual examination appears to be effective in identifying, previous systematic reviews have not evaluated a relevant number of studies and they did not evaluate the accuracy of the clinical examination.

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.

Non-Invasive Diagnostic System Based on Light for Detecting Early-Stage Oral Cancer and High-Risk Precancerous Lesions-Potential for Dentistry

Simple Summary

The early detection of oral cancer and oral potentially malignant disorders can facilitate minimum intervention and subsequent improvements in prognosis and quality of life after treatment. Recently, several non-invasive adjunctive fluorescence-based detection systems have improved the accuracy of detection and diagnosis of oral cancer and oral potentially malignant disorders. This article summarizes current knowledge about fluorescence-based diagnostic methods and discusses their benefits and drawbacks from a clinical viewpoint.

Abstract

Oral health promotion and examinations have contributed to the early detection of oral cancer and oral potentially malignant disorders, leading to the adaptation of minimally invasive therapies and subsequent improvements in the prognosis/maintenance of the quality of life after treatments. However, the accurate detection of early-stage oral cancer and oral epithelial dysplasia is particularly difficult for conventional oral examinations because these lesions sometimes resemble benign lesions or healthy oral mucosa tissues. Although oral biopsy has been considered the gold standard for accurate diagnosis, it is deemed invasive for patients. For this reason, most clinicians are looking forward to the development of non-invasive diagnostic technologies to detect and distinguish between cancerous and benign lesions. To date, several non-invasive adjunctive fluorescence-based detection systems have improved the accuracy of the detection and diagnosis of oral mucosal lesions. Autofluorescence-based systems can detect lesions as a loss of autofluorescence through irradiation with blue-violet lights. Photodynamic diagnosis using 5-aminolevulinic acid (ALA-PDD) shows the presence of very early oral cancers and oral epithelial dysplasia as a red fluorescent area. In this article, currently used fluorescence-based diagnostic methods are introduced and discussed from a clinical point of view.

Minimally invasive procedures for the recognition and diagnosis of oral precancer and cancer

Oral cancer represents a blend of genetic and epigenetic instability. Many a times, oral cancer occurs in the background of oral potentially malignant disorders (OPMDs), which could be easily detected and diagnosed. Various diagnostic aids have been explored for early detection of oral cancer. Some of the minimally invasive (chair-side diagnostic) procedures such as vital staining and light-based systems are used widely in the clinical practice as well as in the hospital setting owing to their simple and easy operability. In addition, these chair-side diagnostic procedures offer relatively good sensitivity and specificity despite some of their limitations. These diagnostic tools could complement good clinical history and thorough examination of patients for early detection of oral precancer and cancer.

A Way Forward for Cancer Chemoprevention: Think Local

As cells progress through carcinogenesis, the associated exponential expansion of genetic and molecular aberrations and resultant heterogeneity make therapeutic success increasingly unattainable. Therapeutic intervention at early stages of carcinogenesis that occurs within the primary organ and in the face of a lower burden of molecular aberrations, constitutes a basic tenet of cancer chemoprevention, and provides a situation that favors a greater degree of therapeutic efficacy compared with that of advanced cancer. A longstanding barrier to chemoprevention relates to the requirement for essentially no systemic toxicity, and the fact that when large numbers of people are treated, the emergence of systemic toxicity is almost universal. A rational means to address this in fact relates to a second basic tenet of the chemopreventive strategy: the focus of therapeutic intervention is to disrupt a process that is in essence localized to a single organ. Based upon this consideration, a strategy which is based upon local delivery of therapeutics to an at-risk organ will achieve therapeutic efficacy while avoiding systemic delivery and its associated toxicity. This article will review the rationale for undertaking such an approach, describe successful clinical achievements based on this strategy, describe ongoing efforts to expand the impact of this approach, and together will highlight the high impact that this approach has already had on the field as well as its extremely high potential for future impact. Cancer Prev Res; 10(1); 14-35. ©2016 AACR.

The limitations of the clinical oral examination in detecting dysplastic oral lesions and oral squamous cell carcinoma

BACKGROUND

The clinical oral examination (COE) is the criterion standard for the initial detection of oral lesions that harbor dysplasia or oral squamous cell carcinoma (OSCC) at an early stage when they are most treatable. The authors conducted a systematic review to assess the effectiveness of the COE in predicting histologic diagnosis of dysplasia or OSCC.

METHODS

The authors conducted automated searches of PubMed, Web of Knowledge and the Cochrane Library from 1966 through 2010 for randomized controlled trials and observational studies that included the terms "oral mucosal lesion screening" and "oral lesions." They determined the quality (sensitivity, specificity, positive predictive value, negative predictive value and diagnostic odds ratio) of selected studies by using the Quality Assessment of Diagnostic Accuracy Studies tool.

RESULTS

The overall diagnostic odds ratio was 6.1 (95 percent confidence interval, 2.1-17.6); therefore, the COE was considered to have poor overall performance as a diagnostic method for predicting dysplasia and OSCC.

CLINICAL IMPLICATIONS

On the basis of the available literature, the authors determined that a COE of mucosal lesions generally is not predictive of histologic diagnosis. The fact that OSCCs often are diagnosed at an advanced stage of disease indicates the need for improving the COE and for developing adjuncts to help detect and diagnose oral mucosal lesions.

A phase I trial of aminolevulinic acid-photodynamic therapy for treatment of oral leukoplakia

BACKGROUND

Photodynamic therapy with aminolevulinic acid (ALA PDT) for oral leukoplakia has shown promising effects in regression of oral leukoplakia. Although ALA has been extensively studied and is an ideal photosensitizer, the optimal light dose for treatment of oral leukoplakia has not been determined. We conducted a phase I study to determine MTD and DLT of PDT in patients treated with ALA for leukoplakia.

METHODS

Patients with histologically confirmed oral leukoplakia received a single treatment of ALA PDT in cohorts with escalating doses of light (585nm). Clinical, histologic, and biologic markers were assessed.

RESULTS

Analysis of 11 participants is reported. No significant toxicity from ALA PDT was observed in patients who received ALA with a light dose of up to 4J/cm(2). One participant experienced transient grade 3 transaminase elevation due to ALA. One participant had a partial clinical response 3months after treatment. Biologic mucosal risk markers showed no significant associations. Determination of MTD could not be accomplished within a feasible timeframe for completion of the study.

CONCLUSIONS

ALA PDT could be safely administered with a light dose up to 4J/cm(2) and demonstrated activity. Larger studies are needed to fully elucidate the MTD and efficacy of ALA-PDT.

Optical imaging modalities for biomedical applications

Optical photographic imaging is a well known imaging method that has been successfully translated into biomedical applications such as microscopy and endoscopy. Although several advanced medical imaging modalities are used today to acquire anatomical, physiological, metabolic, and functional information from the human body, optical imaging modalities including optical coherence tomography, confocal microscopy, multiphoton microscopy, multispectral endoscopy, and diffuse reflectance imaging have recently emerged with significant potential for non-invasive, portable, and cost-effective imaging for biomedical applications spanning tissue, cellular, and molecular levels. This paper reviews methods for modeling the propagation of light photons in a biological medium, as well as optical imaging from organ to cellular levels using visible and near-infrared wavelengths for biomedical and clinical applications.

New frontier in hypericin-mediated diagnosis of cancer with current optical technologies

Photosensitizers (PSs) have shown great potentials as molecular contrast agents in photodynamic diagnosis (PDD) of cancer. While the diagnostic values of PSs have been proven previously, little efforts have been put into developing optical imaging and diagnostic algorithms. In this article, we review the recent development of optical probes that have been used in conjunction with a potent PS, hypericin (HY). Various fluorescence techniques such as laser confocal microscopy, fluorescence urine cytology, endoscopy and endomicroscopy are covered. We will also discuss about image processing and classification approaches employed for accurate PDD. We anticipate that continual efforts in these developments could lead to an objective PDD and complete surgical clearance of tumors. Recent advancements in nanotechnology have also opened new horizons for PSs. The use of biocompatible gold nanoparticles as carrier for enhanced targeted delivery of HY has been attained. In addition, plasmonic properties of nanoparticles were harnessed to induce localized hyperthermia and to manage the release of PS molecules, enabling a better therapeutic outcome of a combined photodynamic and photothermal therapy. Finally, we discuss how nanoparticles can be used as contrast agents for other optical techniques such as optical coherence tomography and surface-enhanced Raman scattering imaging.

DEVELOPMENT OF A LASER CONFOCAL ENDOMICROSCOPE FOR IN VIVO FLUORESCENCE IMAGING

Malignancies of the oral cavity are conventionally diagnosed by white light endoscopy, biopsy and histopathology. However, it is often difficult to distinguish between benign lesions and premalignant or early lesions. There is a need for a more definitive, non-invasive technique for diagnosis of oral cavity lesions. A laser confocal endomicroscope offers non-invasive surface and subsurface imaging of tissue. We investigated its potential for fluorescence imaging of the oral cavity using hypericin, fluorescein and aminolevulinic acid. Fluorescence imaging was carried out both in vivo and on resected tissue samples of the oral cavity in both humans and animal models. Good structural images of the oral cavity were obtained. Morphological differences between normal and lesion tissue can be distinguished. The use of Pharmasolve® enhanced the subsurface depth from which images can be obtained. Our results show that laser confocal fluorescence endomicroscopy has great potential for the diagnosis of oral cavity malignancies.

Advances in bio-optical imaging for the diagnosis of early oral cancer

Oral cancer is among the most common malignancies worldwide, therefore early detection and treatment is imperative. The 5-year survival rate has remained at a dismal 50% for the past several decades. The main reason for the poor survival rate is the fact that most of the oral cancers, despite the general accessibility of the oral cavity, are not diagnosed until the advanced stage. Early detection of the oral tumors and its precursor lesions may be the most effective means to improve clinical outcome and cure most patients. One of the emerging technologies is the use of non-invasive in vivo tissue imaging to capture the molecular changes at high-resolution to improve the detection capability of early stage disease. This review will discuss the use of optical probes and highlight the role of optical imaging such as autofluorescence, fluorescence diagnosis (FD), laser confocal endomicroscopy (LCE), surface enhanced Raman spectroscopy (SERS), optical coherence tomography (OCT) and confocal reflectance microscopy (CRM) in early oral cancer detection. FD is a promising method to differentiate cancerous lesions from benign, thus helping in the determination of adequate resolution of surgical resection margin. LCE offers in vivo cellular imaging of tissue structures from surface to subsurface layers and has demonstrated the potential to be used as a minimally invasive optical biopsy technique for early diagnosis of oral cancer lesions. SERS was able to differentiate between normal and oral cancer patients based on the spectra acquired from saliva of patients. OCT has been used to visualize the detailed histological features of the oral lesions with an imaging depth down to 2–3 mm. CRM is an optical tool to noninvasively image tissue with near histological resolution. These comprehensive diagnostic modalities can also be used to define surgical margin and to provide a direct assessment of the therapeutic effectiveness.

Clinical application of fluorescence endoscopic imaging using hypericin for the diagnosis of human oral cavity lesions

Background:

Diagnosis of oral cancer is conventionally carried out using white light endoscopy and histopathology of biopsy samples. However, oral tumours are mostly superficial and the lesion and its margins can be difficult to visualise under white light. We present clinical data on fluorescence diagnostic imaging of oral lesions using hypericin, a plant-based photosensitiser.

Methods:

Fluorescence images of lesions and normal tissue were captured using an endoscope after hypericin administration. The images were analysed to extract their colour parameters, which, along with the red-to-blue intensity ratios, were analysed and used to discriminate between tissue types. The results were correlated with those from histopathology.

Results:

The red-to-blue intensity ratio increased from normal to hyperplastic to cancerous tissue and was a good parameter to discriminate between these tissue types, with sensitivity and specificity levels of 90% and above.

Conclusion:

Our results show that hypericin fluorescence imaging has the potential to be used for the clinical diagnosis of oral cancer. Further study to enhance the clinical potential of this technique includes the development of a real-time image processing and analysis system interfaced to the endoscope to enable same-day cancer diagnosis and demarcation of lesion margins in a clinical setting.

Improved diagnosis of oral premalignant lesions in submucous fibrosis patients with 5-aminolevulinic acid induced PpIX fluorescence

We investigate the possibility of using ALA-derived PpIX fluorescence spectroscopy for the detection of epithelial hyperkeratosis (EH) or epithelial dysplasia (ED) lesions in oral submucous fibrosis (OSF) patients that could not be found by autofluorescence spectroscopy. Twenty percent of ALA solution gel was applied onto oral neoplasia and surrounding normal tissue [normal oral mucosa (NOM)] for 90 min. Fluorescence emission spectra were measured under 410 nm excitation. Generally, the most intense fluorescence emission peaks occurred at 460 and 630 nm. The ratios of the area under red peak (630+/-10 nm) to the area under blue peak (460+/-10 nm), denoted as RB, were calculated. We found that OSF mucosa has the lowest RB value, followed by NOM, EH on OSF, and ED on OSF. An ANOVA test showed significant differences between OSF, NOM, EH on OSF, and ED on OSF (p<0.05). However, measurements of autofluorescence (i.e., before ALA application) show no significant differences between OSF, NOM, EH on OSF, and ED on OSF (ANOVA test, p>0.05). These results indicate that ALA-induced PpIX fluorescence spectroscopy could be used to identify the premalignant lesions on oral fibrotic mucosa, which could not be found by autofluorescence.

Endoscopic image analysis of photosensitizer fluorescence as a promising noninvasive approach for pathological grading of bladder cancer in situ

Our aim is to apply image analysis on photosensitizer fluorescence and compare the relationship between histopathology and endoscopic fluorescence imaging. The correlation between hypericin fluorescence and histopathology of diseased tissue was explored in a clinical study involving 58 fluorescence cystoscopic images from 23 patients. Based on quantification of fluorescence colorimetric parameters extracted from the image analysis, diagnostic functions were developed to pathologically classify the bladder cancer. Our preliminary results show that the differences in fluorescence intensity ratios among the three different grades of bladder cancer are statistically significant. The results also show a decrease in macroscopic fluorescence intensity that correlated with higher cancer grades. By combining both the red-to-green and red-to-blue fluorescence intensity ratios into a 2-D scatter plot and defining diagnostic linear discrimination functions on the data points, this technique is able to yield an average sensitivity and specificity of around 68.6% and 86.1%, respectively, for pathological cancer grading of the three different grades of bladder cancer in our study. We conclude that our proposed approach in applying colorimetric intensity ratio analysis on hypericin fluorescence shows potential to optically grade bladder cancer in situ.

Laser confocal endomicroscopy as a novel technique for fluorescence diagnostic imaging of the oral cavity

Malignancies of the oral cavity are conventionally diagnosed by white light endoscopy, biopsy, and histopathology. However, it is often difficult to distinguish between benign and premalignant or early lesions. A laser confocal endomicroscope (LCE) offers noninvasive, in vivo surface and subsurface fluorescence imaging of tissue. We investigate the use of an LCE with a rigid probe for diagnostic imaging of the oral cavity. Fluorescein and 5-aminolevulinic acid (ALA) were used to carry out fluorescence imaging in vivo and on resected tissue samples of the oral cavity. In human subjects, ALA-induced protoporphyrin IX (PpIX) fluorescence images from the normal tongue were compared to images obtained from patients with squamous cell carcinoma (SCC) of the tongue. Using rat models, images from normal rat tongues were compared to those from carcinogen-induced models of SCC. Good structural images of the oral cavity were obtained using ALA and fluorescein, and morphological differences between normal and lesion tissue can be distinguished. The use of a pharmaceutical-grade solvent Pharmasolve enhanced the subsurface depth from which images can be obtained. Our initial results show that laser confocal fluorescence endomicroscopy has potential as a noninvasive optical imaging method for the diagnosis of oral cavity malignancies.

ALA-Induced Fluorescence in the Canine Oral Cavity

OBJECTIVE

We examined whether 5-aminolevulinic acid (ALA) could enhance the spectroscopic contrast between normal and diseased oral tissues, without prolonged photosensitivity.

BACKGROUND DATA

ALA is a promising photosensitizing agent.

METHODS

Adose of 25 mg/kg of ALA was administered intravenously to five dogs with gingivitis and three dogs with oral cancer, respectively. Fluorescence was recorded from the diseased sites in the oral cavity in addition to normal sites.

RESULTS

ALA-induced proto-porphyrin IX fluorescence at all gingivitis sites reached a peak in 2-3 h and returned to baseline in 24 h. Fluorescence from the gingivitis site was observed earlier and was higher than the fluorescence from the normal site. For dogs with cancer, fluorescence from the cancerous sites occurred earlier in time compared to gingivitis sites and was comparatively higher in intensity.

CONCLUSION

The fluorescence from the diseased sites was found to be higher than the normal site. Clinical and fluorescence data suggest that a dose of 25 mg/kg may be satisfactory for diagnostic purposes and would have minimal side effects.

The status of in vivo autofluorescence spectroscopy and imaging for oral oncology

Autofluorescence spectroscopy and imaging have been studied for the early detection and classification of (pre)malignancies of the oral mucosa. In the present review we will give an overview of the literature on autofluorescence imaging and spectroscopy for various clinical questions. From the studies performed so far we hope to conclude whether autofluorescence spectroscopy and imaging are helpful in the diagnosis of lesions of the oral mucosa, and if this is the case: for which clinical questions they are suitable. A strong emphasis is put on in vivo human studies of the oral mucosa.

Biophotonic and Other Physical Methods for Characterizing Oral Mucosa

This article discusses biophotonic and other physical methods for characterizing oral mucosa.

Comparison of aminolevulinic-acid-induced fluorescence from normal and inflamed gingiva in the canine model

Fluorescence spectroscopic detection using 5-amino levulinic acid (ALA) may provide an effective, noninvasive approach for early detection of oral cancer. In the present study, the use of ALA-induced fluorescence ratio (red/orange) to differentiate between normal and gingivitis-affected gingiva is investigated. Five dogs with varying degrees of gingivitis are studied. Based on previous studies, a dose of 25 mg/kg of ALA is administered intravenously to the dogs. Autofluorescence and ALA-induced fluorescence from three sites: normal gingiva, pigmented gingiva, and gingivitis, are detected with a fiber optic probe coupled to an optical multichannel analyzer. Four dogs show higher and earlier ALA-induced fluorescence from the gingivitis site as compared to the unpigmented gingiva. In two dogs, ALA-induced fluorescence peaks are seen 15 min after ALA administration. Statistical analysis using mean separation procedures reveal differences in the fluorescence from the various sites in each dog. Using a fluorescence (ratio) cutoff of 1.5, the sensitivity and specificity are found to be 92 and 80%, respectively, 1 h after administration of ALA. The indications from this study-that the characteristic protoporphyrin IX (PpIX) fluorescence is seen earlier and in higher magnitude in more vascular areas of the oral cavity-has implications for oral cancer diagnosis.

The use of digitized endoscopic imaging of 5-ALA-induced PPIX fluorescence to detect and diagnose oral premalignant and malignant lesions in vivo

5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PPIX) fluorescence has shown an outstanding sensitivity for the assessment of oral lesions, but its application was hampered by low specificity due to the high false-positive rates. The purpose of our study was to explore the feasibility of quantifying PPIX fluorescence images to improve the diagnostic specificity for detecting early oral lesions in vivo. A digitized 5-ALA-mediated endoscopic imaging system was utilized to acquire PPIX fluorescence images from in vivo oral tissues. Forty-nine patients (118 biopsies) with known or suspected premalignant or malignant oral lesions were recruited for ALA-PPIX fluorescence endoscopic imaging. The red and blue channels of PPIX fluorescence images were digitized and stored for fluorescence quantification. The red-to-blue intensity ratios were calculated from the fluorescence images to correlate with histologic findings of the biopsies. The results showed that normal oral mucosa exhibited blue color of the back-scattered excitation light in the fluorescence images, whereas the suspicious lesions displayed bright reddish fluorescence. Applying the red-to-blue intensity ratio (I(R)/I(B)) as a diagnostic algorithm yielded a sensitivity of 92% and 98%, and specificity of 96% and 96%, for separating benign tissue from dysplasia, and cancer tissue, respectively, and a sensitivity and specificity of 98% and 92%, respectively, for differentiating cancer tissue from dysplasia in the oral cavity. Our study demonstrates that quantifying ALA-PPIX fluorescence endoscopic images associated with the red-to-blue intensity ratio as a diagnostic algorithm can provide good differentiation between the different stages of oral premalignancy and malignancy (p<0.0001, unpaired 2-sided Student's t-test), and thus has a potential to significantly improve the noninvasive diagnosis and evaluation of early oral neoplasia in vivo.

Topical photodynamic therapy: a new tool in cosmetic dermatology

Topical photodynamic therapy is an evolving relatively new modality in dermatology. While widely used in Europe for treatment of actinic keratoses and skin cancer, topical photodynamic therapy is still relatively unfamiliar in the United States. Approved by the US Food and Drug Administration in 1999, photodynamic therapy is now being evaluated for superficial epidermal tumors, acne, and cosmetic applications. This article reviews recent advances in this field, with emphasis on skin rejuvenation, acne, and hair removal.