The efficacy of direct tissue fluorescence visualization in screening for oral premalignant lesions in general practice: an update

Early Detection of Oral Potentially Malignant Disorders: A Review on Prospective Screening Methods with Regard to Global Challenges

Oral cancer is a cancer type that is widely prevalent in low-and middle-income countries with a high mortality rate, and poor quality of life for patients after treatment. Early treatment of cancer increases patient survival, improves quality of life and results in less morbidity and a better prognosis. To reach this goal, early detection of malignancies using technologies that can be used in remote and low resource areas is desirable. Such technologies should be affordable, accurate, and easy to use and interpret. This review surveys different technologies that have the potentials of implementation in primary health and general dental practice, considering global perspectives and with a focus on the population in India, where oral cancer is highly prevalent. The technologies reviewed include both sample-based methods, such as saliva and blood analysis and brush biopsy, and more direct screening of the oral cavity including fluorescence, Raman techniques, and optical coherence tomography. Digitalisation, followed by automated artificial intelligence based analysis, are key elements in facilitating wide access to these technologies, to non-specialist personnel and in rural areas, increasing quality and objectivity of the analysis while simultaneously reducing the labour and need for highly trained specialists.

Autofluorescence Image-Guided Endoscopy in the Management of Upper Aerodigestive Tract Tumors

At this juncture, autofluorescence and narrow-band imaging have resurfaced in the medicine arena in parallel with current technology advancement. The emergence of newly developed optical instrumentation in addition to the discovery of new fluorescence biomolecules have contributed to a refined management of diseases and tumors, especially in the management of upper aerodigestive tract tumors. The advancement in multispectral imaging and micro-endoscopy has also escalated the trends further in the setting of the management of this tumor, in order to gain not only the best treatment outcomes but also facilitate early tumor diagnosis. This includes the usage of autofluorescence endoscopy for screening, diagnosis and treatment of this tumor. This is crucial, as microtumoral deposit at the periphery of the gross tumor can be only assessed via an enhanced endoscopy and even more precisely with autofluorescence endoscopic techniques. Overall, with this new technique, optimum management can be achieved for these patients. Hence, the treatment outcomes can be improved and patients are able to attain better prognosis and survival.

Prediction of the risk of cancer and the grade of dysplasia in leukoplakia lesions using deep learning

OBJECTIVES

To estimate the probability of malignancy of an oral leukoplakia lesion using Deep Learning, in terms of evolution to cancer and high-risk dysplasia.

MATERIALS AND METHODS

A total of 261 oral leukoplakia lesions with a mean of 5.5 years follow-up were analysed from standard digital photographs. A deep learning pipeline composed by a U-Net based segmentation of the lesion followed by a multi-task CNN classifier was used to predict the malignant transformation and the risk of dysplasia of the lesion. An explainability heatmap is constructed using LIME in order to interpret the decision of the model for each output.

RESULTS

A Dice coefficient of 0.561 was achieved on the segmentation task. For the prediction of a malignant transformation, the model provided a sensitivity of 1 with a specificity of 0.692. For the prediction of high-risk dysplasia, the model achieved a specificity of 0.740 and a sensitivity of 0.928.

CONCLUSION

The proposed model using deep learning can be a helpful tool for predicting the possible malignant evolution of oral leukoplakias. The generated heatmap provides a high confidence on the output of the model and enables its interpretability.

Early Diagnosis on Oral and Potentially Oral Malignant Lesions: A Systematic Review on the VELscope® Fluorescence Method

The fluorescence method is an innovative technique used by pathologists for examining body mucosa, and for the abnormalities tissue screening, potentially leading to the earlier discovery of pre-cancer, cancer or other disease processes. The early detection is one of the best mechanisms for enabling treatment success, increasing survival rates and maintaining a high quality of life. The purpose of this review is to evaluate the clinical efficiency of this diagnostic tool applied to the oral cavity (VELscope^®). A literature systematic review has been performed. The initial research provided 53 results after applying the inclusion and exclusion criteria, and after a manual screening of the abstracts by the authors, only 25 results were eligible for review. The results and data contained in all the researches, no older than 10 years, were manually evaluated, and provided useful information on this diagnostic method. The VELscope^® mean value about sensitivity and specificity resulted of 70.19% and 65.95%, respectively, by results analysis, but despite this some studies disagree about its clinical effectiveness, and this diagnostic method is still much debated in scientific and clinical medical literature. Surely being able to have efficient and effective tools from this point of view could help the clinician in the diagnosis, and also make timelier the pharmacological or surgical therapy, improving the quality of life of the patient, and in some cases guaranteeing a longer survival term.

Comparative evaluation of autofluorescence imaging and histopathological investigation for oral potentially malignant disorders in Taiwan

OBJECTIVES

Autofluorescence imaging is gaining popularity as an adjunctive test for oral potentially malignant disorders (OPMD). This study evaluated the efficacy of autofluorescence imaging based on the current standard oral mucosal disorder checklist in Taiwan.

MATERIALS AND METHODS

In total, 126 patients suspected to have mucosal disorders at the Division of Oral and Maxillofacial Surgery, Tri-Service General Hospital, Taipei, Taiwan, were enrolled. Following a conventional oral examination by using the oral mucosal disorder checklist and an autofluorescence imaging examination, all participants underwent histopathological examination to access epithelial dysplasia.

RESULTS

Among 126 patients, 68 patients were diagnosis as having an OPMD and 63 having epithelial dysplasia. Autofluorescence imaging exhibited a sensitivity, specificity, positivity predictive value (PPV), negative predictive value (NPV), and accuracy of 77.94%, 35.42%, 63.10%, 53.13%, and 60.34%, respectively, for OPMD and of 88.89%, 43.86%, 63.64%, 78.13%, and 67.50%, respectively, for epithelial dysplasia. After the exclusion of 48 non-OPMD cases according to the checklist, the sensitivity, specificity, PPV, NPV, and accuracy of autofluorescence imaging became 87.50%, 72.73%, 94.23%, 53.33%, and 85.07%, respectively, for epithelial dysplasia.

CONCLUSION

The efficacy of epithelial dysplasia identification and OPMD risk assessment can be increased after the exclusion of the non-OPMD cases through autofluorescence imaging.

CLINICAL RELEVANCE

Autofluorescence imaging is a useful adjunct that can assist specialists in assessing OPMD patients prone to dysplasia without compromising patient care.

Clinical Application of the IllumiScan Fluorescence Visualization Device in Detecting Oral Mucosal Lesions

Objective: Fluorescence visualization devices are screening devices that can be used to examine lesions of the oral mucosa non-invasively. We observed oral squamous cell carcinoma (OSCC) and leukoplakia using the IllumiScan (Shofu, Kyoto, Japan) fluorescence visualization device and examined its usefulness and characteristics.

Methods: We investigated 31 OSCC and nine leukoplakia in patients who were examined using the IllumiScan and treated in our department from January 2017 to February 2018. Images taken with the IllumiScan were analyzed using image analysis software. We also examined the lesions using narrowband imaging (NBI). Additionally, the IllumiScan and NBI images and the non-stained areas of iodine staining method (IOM) were visually evaluated.

Results: The average luminance of OSCC in the keratinized mucosa was significantly lower than that of OSCC in non-keratinized mucosa. The average luminance of OSCC was significantly lower than that of leukoplakia. Even in keratinized mucosa where IOM is impossible to use, the OSCC lesion exhibited fluorescence visualization loss.

Conclusion: The application of the fluorescence visualization device to the oral mucosa may be useful for distinguishing between cancer and normal areas and can be used to detect OSCC in the keratinized mucosa. The use of the IllumiScan in combination with other conventional screening methods may lead to a better diagnosis.

Detection accuracy for epithelial dysplasia using an objective autofluorescence visualization method based on the luminance ratio

The autofluorescence visualization method (AVM) uses blue excitation light to assist in the diagnosis of epithelial dysplasia. It detects epithelial dysplasia as a black area, which is known as fluorescence visualization loss (FVL). In this study, we evaluated the detection accuracy for epithelial dysplasia of the tongue using the objective AVM and assessed its possible clinical utility. Seventy-nine tongue specimens clinically suspected to have leukoplakia or squamous cell carcinoma (SCC) were analyzed. First, the AVM was subjectively performed using the Visually Enhanced Lesion scope (VELscope), and the iodine-staining method was then performed. After biopsy, the histopathological results and the luminance ratio between the lesion and healthy tissue were compared, and a receiver operating characteristic curve was created. The cutoff value for the objective AVM was determined; the lesion was considered FVL-positive or -negative when the luminance ratio was higher or lower than the cutoff value, respectively. The histopathological diagnoses among the 79 specimens were SCC (n=30), leukoplakia with dysplasia (n=34), and leukoplakia without dysplasia (n=15). The cutoff value of the luminance ratio was 1.62, resulting in 66 FVL-positive and 13 FVL-negative specimens. The luminance ratio was significantly higher in the epithelial dysplasia-positive than -negative group (P<0.000 1). The objective AVM showed much higher consistency between histopathological results than did the two methods (kappa statistic=0.656). In conclusion, objective autofluorescence visualization has a potential as an auxiliary method for diagnosis of epithelial dysplasia.

Autofluorescence and Diagnostic Accuracy of Lesions of Oral Mucosa: A Pilot Study

The purpose of this study was to determine the accuracy of autofluorescence techniques for diagnosing oral mucosa lesions, using as reference pattern for comparison the visual diagnosis made by a clinical specialist. A pilot study was conducted with 60 patients divided in a control group without mucosal pathology and a study group with known clinical history for mucosal pathology. Both groups were examined by an oral medicine specialist and by a general dentist who used VELscope(r) system, which applies tissue fluorescence visualization to identify oral mucosal abnormalities. Using the VELscope(r) system, the general dentist made overdiagnosis in two cases and underdiagnosis in one case. The sensitivity and specificity for the oral medicine specialist were 1 (95% CI: 0.884 to 1). For the general dentist, the sensitivity did not improve significantly with the use of VELscope(r) system [0.53 (95% CI: 0.343 to 0.717) versus 0.49 (95% CI: 0.406 to 0.773)] and the specificity was 0.80 (95% CI: 0.614 to 0.923). A limitation of the study is the small sample size, which does not fully represent a population and extrapolation of the data should be done carefully. Based on the obtained results, no clinical benefits were obtained using this VELscope(r) system.

A dielectrophoretic method of discrimination between normal oral epithelium, and oral and oropharyngeal cancer in a clinical setting

Despite the accessibility of the oral cavity to clinical examination, delays in diagnosis of oral and oropharyngeal carcinoma (OOPC) are observed in a large majority of patients, with negative impact on prognosis. Diagnostic aids might help detection and improve early diagnosis, but there remains little robust evidence supporting the use of any particular diagnostic technology at the moment. The aim of the present feasibility first-in-human study was to evaluate the preliminary diagnostic validity of a novel technology platform based on dielectrophoresis (DEP). DEP does not require labeling with antibodies or stains and it is an ideal tool for rapid analysis of cell properties. Cells from OOPC/dysplasia tissue and healthy oral mucosa were collected from 57 study participants via minimally-invasive brush biopsies and tested with a prototype DEP platform using median membrane midpoint frequency as main analysis parameter. Results indicate that the current DEP platform can discriminate between brush biopsy samples from cancerous and healthy oral tissue with a diagnostic sensitivity of 81.6% and a specificity of 81.0%. The present ex vivo results support the potential application of DEP testing for identification of OOPC. This result indicates that DEP has the potential to be developed into a low-cost, rapid platform as an assistive tool for the early identification of oral cancer in primary care; given the rapid, minimally-invasive and non-expensive nature of the test, dielectric characterization represents a promising platform for cost-effective early cancer detection.

Autofluorescence imaging in recurrent oral squamous cell carcinoma

The survival of patients with oral cancer is decreased by locoregional recurrence after an initial multimodal treatment. In order to identify lesions in the oral cavity for a possible recurrence, clinical evaluation as well as MRI or CT scanning is advised. The evaluation of mucosa lesions is hampered by changes related to radio- and chemotherapy as well as reconstruction with tissue flaps. Several techniques for easier identification of tissue abnormalities in the oral cavity have been advocated as adjuncts in order to facilitate identification. Especially methods using altered tissue fluorescence have gained much interest during the last decade. The aim of our prospective study was to evaluate fluorescence properties of undiagnosed mucosa lesions with the VELscope device in patients with multimodal treated oral cancer prior to histological confirmation. In total, 41 patients with a history of oral squamous cell carcinomas (OSCC) (19 females and 22 males) with undiagnosed mucosa lesions where included in the study. After clinical evaluation, examination and documentation using the VELscope® device were performed. Then, an incisional biopsy was performed. An autofluorescence loss indicating a malignant or dysplastic mucosa condition could be detected in six patients (14.6 %); however, only one OSCC and one SIN revealed a complete autofluorescence loss. In four patients, OSCC was present in lesions with retained autofluorescence. Sensitivity and specificity for the VELscope® examination to identify malignant oral lesions by autofluorescence were 33.3 and 88.6 %, respectively. The positive and negative predictive values were 33.3 and 88.6 %, respectively. No statistical correlation between gender and lesion appearance versus autofluorescence loss could be detected. In contrast to mucosa lesions in patients with no prior treatment, the autofluorescence evaluation with the VELscope reveals no additional information in our analysis. Accordingly, invasive biopsies as gold standard are still needed to get sufficient evidence regarding potential malignancy in patients after multimodal treatment for oral cancer.

The use of light-based (optical) detection systems as adjuncts in the detection of oral cancer and oral potentially malignant disorders: a systematic review

INTRODUCTION

In recent decades, optical techniques utilising the principles of chemiluminescence and tissue autofluorescence have emerged to facilitate the early detection of any oral mucosal changes suspicious of cancer.

PURPOSE

To evaluate the effectiveness of devices that utilise the principles of chemiluminescence and tissue autofluorescence as adjuncts in the detection of oral cancer and oral potentially malignant disorders (OPMDs).

METHODS

A systematic review of the published literature to evaluate the effectiveness of the ViziLite(®) and ViziLite(®) Plus with toluidine blue, MicroLux™/DL and the VELscope™ as aids in the detection of oral cancer and OPMDs.

RESULTS

Twenty-five primary studies published between 2004 and 2013 satisfied our criteria for selection - 13 utilised chemiluminescence and 12 tissue autofluorescence. Some had utilised both study methods on the same population. Chemiluminescence shows good sensitivity at detecting any OPMDs and oral cancer. However, it preferentially detects leukoplakia and may fail to spot red patches. The additive use of toluidine blue may improve specificity. Tissue autofluorescence is sensitive at detecting white, red and white and red patches, and the area of fluorescence visualisation loss (FVL) often extends beyond the clinically visible lesion. However, in addition to OPMDs, VELScope may detect erythematous lesions of benign inflammation resulting in false-positive test results.

CONCLUSION

There is limited evidence for their use in primary care, and these tools are better suited to specialist clinics in which there is a higher prevalence of disease and where experienced clinicians may better discriminate between benign and malignant lesions.

Intraoperative efficiency of fluorescence imaging by Visually Enhanced Lesion Scope (VELscope) in patients with bisphosphonate related osteonecrosis of the jaw (BRONJ)

OBJECTIVES

The purpose of this study was to determine the potential of tissue fluorescence imaging by using Visually Enhanced Lesion Scope (VELscope) for the detection of osteonecrosis of the jaw induced by bisphosphonates (BRONJ).

METHODS

We investigated 20 patients (11 females and 9 males; mean age 74 years, standard deviation ± 6.4 years), over a period of 18 month with the diagnosis of BRONJ in this prospective cohort study. All patients received doxycycline as a fluorescending marker for osseous structures. VELscope has been used intraoperatively using the loss of fluorescence to detect presence of osteonecrosis. Osseous biopsies were taken to confirm definite histopathological diagnosis of BRONJ in each case.

RESULTS

Diagnosis of BRONJ was confirmed for every patient. In all patients except one, VELscope was sufficient to differentiate between healthy and necrotic bone by visual fluorescence retention (VFR) and visual fluorescence loss (VFL). 19 cases out of a total of 20 showed no signs of recurrence of BRONJ during follow-up (mean 12 months, range 4-18 months).

CONCLUSION

VELscope examination is a suitable tool to visualize necrotic areas of the bone in patients with bisphosphonate related osteonecrosis of the jaw. Loss of fluorescence in necrotic bone areas is useful intraoperatively as a tool for fluorescence-guided bone resection with relevant clinical interpretation.