Evaluation of the Accuracy of Liquid-Based Oral Brush Cytology in Screening for Oral Squamous Cell Carcinoma

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.

Effectiveness of adjunctive screening tools for potentially malignant oral disorders and oral cancer: A systematic review

Background and objectives

To enhance the abilities of healthcare professionals to make informed treatment decisions and establish accurate diagnoses, it is essential to assess the diagnostic reliability of different adjunctive aids. This systematic review aimed to compare the accuracy of various adjunctive methods for diagnosing suspected oral cancer (OC) or potentially malignant oral disorders (OPMD) in adults against histopathological investigative results.

Materials and methods

The review protocol registered in the PROSPERO database (CRD42023463525) was developed in strict accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis-Diagnostic Test Accuracy checklist. A comprehensive electronic search was conducted to identify relevant research articles published between January 2014 and April 2023 using the PubMed and EBSCO databases. The research question was meticulously structured following the participants' index test, reference standard, target condition, and study setting framework. To evaluate methodological quality and assess the risk of bias (RoB), the Quality Assessment for Diagnostic Accuracy Studies-2 tool was used.

Results

An initial search yielded 483 publications, which were reduced to 278 after removal of duplicates. Finally, 85 publications underwent full-text review by two investigators, which lead to 29 studies that met the inclusion criteria. Among these, 7% had a low RoB, 72% had an unclear RoB, and 21% had a high RoB. Applicability concerns were expressed in 59% of the studies with low concern, 31% with unclear quality evidence of concern, and 10% with high concern.

Conclusion

The review findings support the use of these diagnostic methods as valuable adjuncts to biopsy for the early detection of various OPMD and OC. They also highlight the importance of regular screening and awareness in reducing the global burden of OC, while acknowledging that they cannot replace the gold standards of surgical biopsy and histopathological evaluation.

Dual Sec62/Ki67 immunocytochemistry of liquid-based cytological preparations represents a highly valid biomarker for non-invasive detection of head and neck squamous cell carcinomas

BACKGROUND

Head and neck squamous cell carcinomas (HNSCC) are frequently diagnosed in advanced stages, which limits therapeutic options and results in persistently poor patient outcomes. The aim of this study was to use liquid-based swab cytology (LBC) in combination with dual immunocytochemical detection of migration and proliferation markers Sec62 and Ki67 in order to allow non-invasive early detection of HNSCC as well as to analyse the diagnostic validity of this method for predicting the malignancy of suspicious oral lesions.

METHODS

104 HNSCC patients and 28 control patients, including healthy patients (n = 17), papilloma (n = 1) and leukoplakia patients (n = 10), were included in this study. For all patients, an LBC swab followed by simultaneous immunocytochemical detection of Sec62 and Ki67 was performed. Immunocytochemical as well as cytopathological results were correlated with histological diagnoses and clinical findings.

RESULTS

All HNSCC patients (100%) showed dual Sec62/Ki67 positivity, and all control patients except for the papilloma patient were negative for Sec62/Ki67 (96.4%), resulting in a 100% sensitivity and 96.4% specificity of Sec62/Ki67 dual stain for non-invasive detection of HNSCC. The positive predictive value was 99% and the negative predictive value was 100%. Sec62 expression levels showed a positive correlation with tumour de-differentiation (p = 0.0489).

CONCLUSION

Simultaneous immunocytochemical detection of Sec62/Ki67 using LBC represents a promising non-invasive and easy-to-apply tool for the early detection of HNSCC in routine clinical practice. This novel technique can help to avoid incisional biopsies and reduce the frequency with which general anaesthesia is used in diagnostic procedures in patients with suspicious oral lesions.

Evaluation of oral brush liquid-based cytology for oral squamous cell carcinoma: a comparative study of cytological and histological diagnoses at a single center

PURPOSE

Liquid-based cytology is highly useful in oral cytology. However, there are only few reports on the accuracy of this method. The current study aimed to compare oral liquid-based cytological and histological diagnoses and to evaluate items that should be considered in oral cytological diagnosis for oral squamous cell carcinoma.

METHODS

We included 653 patients who underwent both oral cytological and histological examinations. Data on sex, specimen collection region, cytological and histological diagnoses, and histological images were reviewed.

RESULTS

The overall male-to-female ratio was 1:1.18. The tongue was the most common specimen collection region, followed by the gingiva and buccal mucosa. The most common cytological examination result was negative (66.8%), followed by doubtful (22.7%) and positive (10.3%). The sensitivity, specificity, positive predictive value, and negative predictive value of cytological diagnosis were 69%, 75%, 38%, and 92%, respectively. Approximately 8.3% of patients with a negative cytological diagnosis had a histological diagnosis of oral squamous cell carcinoma. Furthermore, 86.1% of histopathologic images of cytology-negative squamous cell carcinomas exhibited well-differentiated keratinocytes lacking atypia on the surface. The remaining patients developed recurrence, or they had low cell counts.

CONCLUSION

Liquid-based cytology is useful in screening oral cancer. However, a cytological diagnosis of superficial-differentiated oral squamous cell carcinoma is occasionally inconsistent with the histological diagnosis. Therefore, histological and cytological examinations should be performed if tumor-like lesions are suspected clinically.

Evaluation of Static DNA Ploidy Analysis Using Conventional Brush Biopsy-Based Cytology Samples as an Adjuvant Diagnostic Tool for the Detection of a Malignant Transformation in Potentially Oral Malignant Diseases: A Prospective Study

BACKGROUND

The accuracy of DNA image cytometry as an investigation method for potentially malignant disorders of the oral cavity is currently still a subject of controversy, due to inconsistently applied definitions of DNA aneuploidy, small cohorts and different application techniques of the method. The aim of this study was to examine the accuracy of the method as a supplementary diagnostic tool in addition to the cytological examination using internationally consented definitions for DNA aneuploidy.

METHODS

A total of 602 samples from 467 patients with various oral lesions were included in this prospective study. Brush biopsies from each patient were first cytologically examined and categorized by a pathologist, second evaluated using DNA image cytometry, and finally compared to either histological biopsy result or clinical outcome.

RESULTS

Using the standard definition of DNA aneuploidy, we achieved a sensitivity of 93.5%, a positive predictive value for the detection of malignant cells of 98.0%, and an area under the curve of 0.96 of DNA ploidy analysis for the detection of severe oral epithelial dysplasia, carcinoma in situ or oral squamous cell carcinoma. Importantly, using logistic regression and a two-step model, we were able to describe the increased association between DNA-ICM and the detection of malignant cells (OR = 201.6) as a secondary predictor in addition to cytology (OR = 11.90).

CONCLUSION

In summary, this study has shown that DNA ploidy analysis based on conventional specimens of oral brush biopsies is a highly sensitive, non-invasive, patient-friendly method that should be considered as an additional diagnostic tool for detecting malignant changes in the oral cavity.

Retrospective evaluation of the oral brush biopsy in daily dental routine - an effective way of early cancer detection

OBJECTIVES

Oral brush biopsies are a well researched index for early detection of oral cancer in specialised centers. But the performance of the exfoliative biopsy is not yet researched in daily dental routine.

METHODS

Private dentists and private oral surgeons in Germany took brush biopsies out of 814 suspicious lesions from 670 patients using the Orcellex brush while regular dental appointments. The analyses of the biopsies were performed by the Cytological Laboratory of Bonn (CLB) using liquid-based cytology.

RESULTS

The final results were 74 oral squamous cell carcinomas and one verrucous carcinoma, histological proven, 232 cases of leukoplakia, 242 cases of lichen planus, 17 cases of erythroplakia, 259 cases of benign inflammatory, traumatic or hyperplastic oral lesions. The sensitivity for the detection of cancer cells using brush biopsy archived 100%, the specificity for the detection of non-neoplastic cells was 86.5%. The positive predictive value was 43.1%, the negative predicative value was at 100%.

CONCLUSION

The oral brush biopsy seems to be a sufficient tool for early cancer detection in private dental offices.

CLINICAL RELEVANCE

Generally, practicing dentists do not see various oral squamous cell carcinomas in their careers, so the experience in identifying oral squamous cell carcinomas as such is very low. The brush biopsy might help them in cases of doubt to prevent tumors from expansive growth.

A Systematic Review of Oral Biopsies, Sample Types, and Detection Techniques Applied in Relation to Oral Cancer Detection

Background: Early identification of the stage of oral cancer development can lead to better treatment outcomes and avoid malignant transformation. Therefore, this review aims to provide a comprehensive overview that describes the development of standardized procedures for oral sample collection, characterization, and molecular risk assessment. This can help investigators to choose the appropriate sampling method and downstream analyses for different purposes. Methods: This systematic review was conducted according to the PRISMA guidelines. Using both PubMed and Web of Science databases, four independent authors conducted a literature search between 15 and 21 June 2021. We used key search terms to broaden the search for studies. Non-conforming articles were removed using an EndNote-based and manual approach. Reviewers used a designed form to extract data. Results: This review included a total of 3574 records, after eliminating duplicate articles and excluding papers that did not meet the inclusion criteria. Finally, 202 articles were included in this review. We summarized the sampling methods, biopsy samples, and downstream analysis. The biopsy techniques were classified into tissue and liquid biopsy. The common sequential analysis of tissue biopsy includes histopathological examination such as H&E or IHC to identify various pathogenic features. Meanwhile, liquid samples such as saliva, blood, and urine are analyzed for the purpose of screening to detect mutations in cancer. Commonly used technologies are PCR, RT-PCR, high-throughput sequencing, and metabolomic analysis. Conclusions: Currently, tissue biopsies provide increased diagnostic value compared to liquid biopsy. However, the minimal invasiveness and convenience of liquid biopsy make it a suitable method for mass screening and eventual clinical adoption. The analysis of samples includes histological and molecular analysis. Metabolite analysis is rising but remains scarce.

Usefulness of Five-Parameter System Reconfirmed for Cytopathology of Oral Squamous Cell Carcinoma regardless of Differentiation Degree

BACKGROUND

We previously introduced the Five-Parameter System (FPS), which exclusively evaluates keratinized cellular findings, for use in cytology examinations of oral well-differentiated squamous cell carcinoma (SCC) and carcinoma in situ (CIS) specimens, as they occasionally lack nuclear atypia and can be challenging for categorization by The Bethesda System (TBS). This study was conducted to determine whether FPS parameters are detectable even in oral SCC/CIS specimens with apparent nuclear atypia.

SUMMARY

Oral cytology specimens were obtained together with biopsy tissue samples. They were obtained from 59 malignant (HSIL and SCC) and 29 not-definitely malignant (NILM to ASC-H) specimens diagnosed using TBS. Following re-confirmation of the original TBS categorization, the specimens were re-evaluated using FPS. One or more of the FPS parameters were noted in 69 of 70 malignant specimens examined, of which 11 had been diagnosed by TBS as not-definitely malignant. The remaining one malignant specimen was diagnosed as SCC with only TBS. FPS parameters #1 (concentric arrangement), #2 (large cell number), #3 (bizarre-shaped cells), #4 (keratoglobules), and #5 (uneven filamentous cytoplasm) were observed only in malignant cases, while none were revealed in not-definitely malignant specimens. Finally, TBS supplemented with FPS achieved sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 100%.

KEY MESSAGES

FPS parameters are included in most examinations of oral cytology specimens. Thus, FPS is highly recommended for use in cytology examinations of oral SCC regardless of differentiation degree to confirm judgment based on TBS, a mandatory standard, as well as to cover its limitation of mainly evaluating nuclear atypia. FPS is considered to be an important diagnostic tool for oral cytology, especially in triage cases, which are challenging for TBS. Cytopathology should not be limited to only nuclear findings but be based on whole-cell morphology.

TUBB3 immunostaining improves the diagnostic accuracy of oral liquid-based cytology in squamous cell carcinoma

OBJECTIVE

Although class III beta-tubulin (TUBB3) is not expressed in normal epithelium, its expression in cancers of some organs has been reported. Herein, we investigated TUBB3 expression pattern and level in oral squamous cell carcinoma (SCC), and assessed whether TUBB3 immunostaining could improve the diagnostic accuracy of oral scraping liquid-based cytology (LBC).

METHODS

Paraffin sections of biopsies from 107 patients with primary SCC and 30 patients with squamous papilloma occurred in tongue and gingiva were immunostained for TUBB3. Moreover, 15 LBC samples obtained from the study participants with SCC were also immunostained for TUBB3. Seven LBC samples were false-negative. TUBB3 expression level in each sample was evaluated and classified as 3+, 2+, 1+, and 0.

RESULTS

TUBB3 expression was confirmed in 91.6% of paraffin-embedded SCC specimens. Clear and diffuse positivity (above 2+) was observed in 77.6% of the total cases. In the well-differentiated type, tumour cells in the middle layer of the parenchyma specifically expressed TUBB3. In almost LBC samples, cancerous intermediate cells showed immunopositivity similarly to that of paraffin samples, even if cellular atypia was not clear in Papanicolaou staining.

CONCLUSIONS

TUBB3 immunostaining is useful for diagnosing oral SCC in scraping LBC, especially when samples consist of intermediate cells with little morphological change. Moreover, TUBB3 immunostaining could improve the diagnostic accuracy of oral scraping LBC by reducing false-negative.

Accuracy of liquid-based brush cytology and HPV detection for the diagnosis and management of patients with oropharyngeal and oral cancer

Objectives

This study aims to evaluate the usefulness of liquid-based brush cytology for malignancy diagnosis and HPV detection in patients with suspected oropharyngeal and oral carcinomas, as well as for the diagnosis of tumoral persistence after treatment.

Material and methods

Seventy-five patients with suspicion of squamous cell carcinoma of the oropharynx or oral cavity were included. Two different study groups were analyzed according to the date of the sample collection: (1) during the first endoscopy exploration and (2) in the first control endoscopy after treatment for squamous cell carcinoma. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for malignancy diagnosis as well as for HPV-DNA detection on brush cytologies were assessed.

Results

Before treatment, the brush cytology showed a sensitivity of 88%, specificity of 100%, and accuracy of 88%. After treatment, it showed a sensitivity of 71%, specificity of 77%, and accuracy of 75%. HPV-DNA detection in cytology samples showed a sensitivity of 85%, specificity of 100%, and accuracy of 91% before treatment and an accuracy of 100% after treatment.

Conclusions

Liquid-based brush cytology showed good accuracy for diagnosis of oropharyngeal and oral squamous cell carcinoma before treatment, but its value decreases after treatment. Nevertheless, it is useful for HPV-DNA detection, as well as to monitor the patients after treatment.

Clinical relevance

Brush cytology samples are reliable for the detection of HPV-DNA before and after treatment and may be a useful method to incorporate in the HPV testing guidelines.

Oral Mucosa Could Be an Infectious Target of SARS-CoV-2

The World Health Organization reported that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission is caused by respiratory droplets and aerosols from the oral cavity of infected patients. The angiotensin-converting enzyme 2 (ACE2) is considered the host functional protein for SARS-CoV-2 infection. In this article, we first revealed that the positive proportion of ACE2 expression in gingival cells collected from the gingival sulcus was increased to the same level as the tongue. Our data demonstrate that cells in the gingival sulcus may be a new entry point for the SARS-CoV-2 virus via a high expression of ACE2. In addition, we first evaluated the expression of ACE2 in various sites of the oral cavity with noninvasive, convenient liquid-based cytology. The liquid-based cytology evaluation of oral tissue may provide a novel preventive medical avenue against COVID-19.

Diagnostic tests for oral cancer and potentially malignant disorders in patients presenting with clinically evident lesions

BACKGROUND

Squamous cell carcinoma is the most common form of malignancy of the oral cavity, and is often proceeded by oral potentially malignant disorders (OPMD). Early detection of oral cavity squamous cell carcinoma (oral cancer) can improve survival rates. The current diagnostic standard of surgical biopsy with histology is painful for patients and involves a delay in order to process the tissue and render a histological diagnosis; other diagnostic tests are available that are less invasive and some are able to provide immediate results. This is an update of a Cochrane Review first published in 2015.

OBJECTIVES

Primary objective: to estimate the diagnostic accuracy of index tests for the detection of oral cancer and OPMD, in people presenting with clinically evident suspicious and innocuous lesions.

SECONDARY OBJECTIVE

to estimate the relative accuracy of the different index tests.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: MEDLINE Ovid (1946 to 20 October 2020), and Embase Ovid (1980 to 20 October 2020). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were also searched for ongoing trials to 20 October 2020. No restrictions were placed on the language or date of publication when searching the electronic databases. We conducted citation searches, and screened reference lists of included studies for additional references.

SELECTION CRITERIA

We selected studies that reported the diagnostic test accuracy of the following index tests when used as an adjunct to conventional oral examination in detecting OPMD or oral cavity squamous cell carcinoma: vital staining (a dye to stain oral mucosa tissues), oral cytology, light-based detection and oral spectroscopy, blood or saliva analysis (which test for the presence of biomarkers in blood or saliva).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts for relevance. Eligibility, data extraction and quality assessment were carried out by at least two authors, independently and in duplicate. Studies were assessed for methodological quality using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). Meta-analysis was used to combine the results of studies for each index test using the bivariate approach to estimate the expected values of sensitivity and specificity.

MAIN RESULTS

This update included 63 studies (79 datasets) published between 1980 and 2020 evaluating 7942 lesions for the quantitative meta-analysis. These studies evaluated the diagnostic accuracy of conventional oral examination with: vital staining (22 datasets), oral cytology (24 datasets), light-based detection or oral spectroscopy (24 datasets). Nine datasets assessed two combined index tests. There were no eligible diagnostic accuracy studies evaluating blood or salivary sample analysis. Two studies were classed as being at low risk of bias across all domains, and 33 studies were at low concern for applicability across the three domains, where patient selection, the index test, and the reference standard used were generalisable across the population attending secondary care. The summary estimates obtained from the meta-analysis were: - vital staining: sensitivity 0.86 (95% confidence interval (CI) 0.79 to 0.90) specificity 0.68 (95% CI 0.58 to 0.77), 20 studies, sensitivity low-certainty evidence, specificity very low-certainty evidence; - oral cytology: sensitivity 0.90 (95% CI 0.82 to 0.94) specificity 0.94 (95% CI 0.88 to 0.97), 20 studies, sensitivity moderate-certainty evidence, specificity moderate-certainty evidence; - light-based: sensitivity 0.87 (95% CI 0.78 to 0.93) specificity 0.50 (95% CI 0.32 to 0.68), 23 studies, sensitivity low-certainty evidence, specificity very low-certainty evidence; and - combined tests: sensitivity 0.78 (95% CI 0.45 to 0.94) specificity 0.71 (95% CI 0.53 to 0.84), 9 studies, sensitivity very low-certainty evidence, specificity very low-certainty evidence.

AUTHORS' CONCLUSIONS

At present none of the adjunctive tests can be recommended as a replacement for the currently used standard of a surgical biopsy and histological assessment. Given the relatively high values of the summary estimates of sensitivity and specificity for oral cytology, this would appear to offer the most potential. Combined adjunctive tests involving cytology warrant further investigation. Potentially eligible studies of blood and salivary biomarkers were excluded from the review as they were of a case-control design and therefore ineligible. In the absence of substantial improvement in the tests evaluated in this updated review, further research into biomarkers may be warranted.

Application of the Bethesda system of reporting for cervical cytology to evaluate human papilloma virus induced changes in oral leukoplakia, oral squamous cell carcinoma, and oropharyngeal squamous cell carcinoma: A cytomorphological and genetic study

BACKGROUND

Human papilloma virus (HPV) has a well-established carcinogenic role in certain head and neck cancers. These HPV associated cancers possess unique clinicopathological behavior and exhibits better prognosis than their negative counterparts. Detection through polymerase chain reaction (PCR) has been considered as the "gold standard" but imposes burden in low resource settings. Therefore, in the present study, we assessed the validity of cytomorphological features for the detection of HPV in oral leukoplakia (OL), oral squamous cell carcinoma (OSCC), and oropharyngeal squamous cell carcinoma (OPSCC).

METHODOLOGY

This study included 63 subjects comprising of 25 OL, 26 OSCC, and 12 OPSCC cases. Exfoliated cells were collected and processed for PCR followed by Papanicolaou staining and subsequent grading. Additionally the non-classical signs were evaluated and statistical analysis included Chi-square and Spearman's test.

RESULT

23/63 (36.5%) cases showed PCR positivity for HPV16. Most of the cytomorphological features showed significant correlation for the presence of HPV. A greater sensitivity and specificity was observed in the Bethesda system for reporting cervical cytology (TBS) than the Papanicolaou grading system.

CONCLUSION

We conclude that the non-classic cytological features could be employed in the detection of HPV in low resource settings with improved sensitivity. Liquid based cytology graded using TBS could be suitable for oral cytology in the detection of early atypical changes.

Non-Invasive Early Detection of Oral Cancers Using Fluorescence Visualization with Optical Instruments

Simple Summary

Oral cancer has a high mortality rate. Then, oral cancer screening is needed for early detection and treatment. Fluorescence visualization is non-invasive, convenient, and in real-time, and examinations can be repeated. Our study aimed to show the usefulness of oral cancer screening with fluorescence visualization. A total of 502 patients were performed using fluorescence visualization that was analyzed using subjective and objective evaluation. Results of this study, subjective evaluation for detection oral cancer was high sensitivity and low specificity, while objective evaluation using imaging processing analysis was high sensitivity and high specificity. Therefore, oral cancer screening using fluorescence visualization is useful for the detection of oral cancer. The widespread use of this screening can reduce the mortality rate of oral cancer.

Abstract

Background: Oral cancer screening is important for early detection and early treatment, which help improve survival rates. Biopsy is the gold standard for a definitive diagnosis but is invasive and painful, while fluorescence visualization is non-invasive, convenient, and real-time, and examinations can be repeated using optical instruments. The purpose of this study was to clarify the usefulness of fluorescence visualization in oral cancer screening. Methods: A total of 502 patients, who were examined using fluorescence visualization with optical instruments in our hospitals between 2014 and 2019, were enrolled in this study. The final diagnosis was performed by pathological examination. Fluorescence visualization was analyzed using subjective and objective evaluations. Results: Subjective evaluations for detecting oral cancer offered 96.8% sensitivity and 48.4% specificity. Regarding the objective evaluations, sensitivity and specificity were 43.7% and 84.6% for mean green value, 55.2% and 67.0% for median green value, 82.0% and 44.2% for coefficient of variation of value, 59.6% and 45.3% for skewness, and 85.1% and 75.8% for value ratio. For the sub-analysis of oral cancer, all factors on objective and subjective evaluation showed no significant difference. Conclusions: Fluorescence visualization with subjective and objective evaluation is useful for oral cancer screening.

Optimized liquid-based cytology for the cellular and molecular analysis of oral keratinocytes: A promising diagnostic tool

BACKGROUND

Liquid-based cytology (LBC) has improved exfoliative cytology by facilitating the extraction of more precise information from epithelial cells. The aim of this study was to optimize a protocol using a conventional cytobrush to perform LBC, obtaining oral keratinocytes for their further cellular and molecular analysis.

METHODS

LBC was performed in 30 healthy donors from buccal mucosa. We evaluated the use of diethyl pyrocarbonate (DEPC)-treated Dulbecco's Modified Eagle Medium (DMEM) medium right after the collection of the cells. Cell morphology and viability were determined by Orcein staining and flow cytometry, respectively. RNA was extracted by the trizol method, and evaluated with spectrometry and electrophoresis. Finally, RNA was copied into cDNA and GAPDH and TLR2 genes were amplified by reverse transcription polymerase chain reaction (RT-PCR) and quantitative reverse transcription polymerase chain reaction (RT-qPCR) using specific primers.

RESULTS

Only DEPC-treated DMEM preserved the viability of intact intraepithelial keratinocytes. RNA quantity and quality improves in samples treated with DEPC. RNA integrity is comparable with a cell line control. GAPDH gene was successfully amplified by RT-PCR and RT-qPCR.

CONCLUSIONS

Therefore, LBC performed under these conditions becomes a reproducible technique for the retrieval of intraepithelial oral keratinocytes with good cell viability for cytomorphometric analysis, and extraction of good RNA quality suitable for molecular analyses such as PCR. We propose this LBC protocol as a complementary method to the cellular and molecular study of oral mucosa pathologies; however, it requires further study.

Strategies to improve diagnosis and risk assessment for oral cancer patients

To realise the benefits of new diagnostic techniques for the prediction of oral cancer, further validation and multicentre analyses are needed to determine their clinical impact in contemporary practice.