Sensitivity and Specificity of Oral Brush Biopsy

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.

Adjunctive techniques and diagnostic aids in the early detection of oral premalignant disorders and cancer: An update for the general dental practitioners

Oral cancer (OC), a potentially fatal disease, is a major health concern across the world. It is reported to be the sixth most common cancer in the world with a disappointingly low 5-year survival rate, despite major advances in onco-medicine in the past three decades. The low 5-year-survival rate is associated with late diagnosis of the disease, while OC diagnosed at early stages enjoy a much higher 5-year-survival rate, comparatively. Although the oral cavity is one of the most easily accessible parts of the body for cancer screening, OC is typically diagnosed at later stages. The delay in diagnosis is one of the factors for the poor 5-year survival rate and high mortality and morbidity among patients. Therefore, an early diagnosis is of utmost importance. Visual and tactile examination and scalpel biopsy are still considered the gold standard for definitive diagnosis of oral potentially malignant disorder (OPMD) and OC. Nevertheless, adjunctive techniques could be employed to increase the ability to distinguish benign abnormalities from dysplastic/malignant changes. These would also aid in identifying areas of dysplasia/early OC that are not visible to the naked eye and tackle the delay in diagnosing OPMD/OC. These adjunctive tools are not a replacement for visual and tactile examination but are supplementary aids. They could be used to screen healthy patients for the presence of any occult cancerous change and evaluate the biological potential of clinically abnormal mucosal lesions, thus enabling early recognition and diagnosis which might increase survival rate and reduce mortality and treatment-associated morbidity.

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.

Abrasive cytohistology of squamous epithelial lesions

Objective:

To describe a method to retrieve cellular and tissue elements of oral squamous epithelium obtained by abrasive methods and to conduct investigations by cytohistology.

Method:

We developed a special gelatine pocket suitable for paraffin embedding of sparse material obtained from brush biopsies (BBs). This was subjected to combined evaluation of a cytological (smear) and histological examination of the ‘tissue sections’ – referred as cytohistology. Four diagnostic categories were applied for evaluation. Other special diagnostic methods were also applied in addition to recording dysplasia.

Results:

A total of 51, 755 BBs from suspicious lesions of the oral mucosa (mostly oral potentially malignant disorders – OPMD) were evaluated for the presence of carcinoma or dysplasia; in all, 1.7% were positive, 78.2% were negative for any epithelial atypia, 16.8% atypical and 3.3% inadequate. All BBs also had cytohistological evaluation. A ‘positive’ diagnosis by cytohistology was a reliable indicator of dysplasia or carcinoma, requiring further incisional/excisional biopsy. In the ‘atypical’ category, a variety of lesions were found, about half being dysplasia or carcinoma. This category challenges the clinician for further clinical, therapeutic and/or excisional examination. In ‘negative’ cases with persistence of the lesion, a re-examination in 1-year sequence is recommended.

Conclusion:

Cytohistology of material derived by abrasive methods allows earlier detection of dysplasia/carcinoma. A number of additional oncological and non-oncological findings make this method a valuable non-invasive diagnostic procedure for oral mucosal lesions.

The prognostic value of GLUT-1 staining in the detection of malignant transformation in oral mucosa

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) ranks as the sixth most common tumor entity worldwide. Unfortunately, the multimodal treatment consisting of surgery, radiation, and chemotherapy does not show the desired efficacy. The intent of this study was to evaluate the sensitivity and specificity of an oral brush biopsy in combination with glucose transporter (GLUT)-1 staining in identifying premalignant and malignant lesions.

METHODS

A total of 72 patients were included in the study, divided into four diagnostic subgroups (24 healthy, 15 carcinoma, 18 leukoplakia, 15 oral lichen planus). Oral brush biopsies were taken and analyzed for GLUT-1 expression by immunocytologic staining. Incisional biopsy served as the gold standard.

RESULTS

Twelve (80 %) of the 15 carcinomas, nine (50 %) of the 18 leukoplakia, nine (60 %) of the 15 oral lichen planus, and none of the healthy specimens stained positive for GLUT-1. This resulted in a sensitivity rate of 80 % and a specificity rate of 68.42 %. Diagnostic accuracy was 70.83 % based on the correct diagnoses in 51 of 72 patients.

CONCLUSION

An oral brush biopsy can easily be performed throughout the entire oral cavity, is noninvasive, and shows high sensitivity and specificity rates with conventional cytology or computer-assisted analysis.

CLINICAL RELEVANCE

The significance of GLUT-1-specific staining with an oral brush biopsy is more limited than expected but could be used as an additional tool in detecting malignant transformation in the oral cavity.

Meta-analysis of two computer-assisted screening methods for diagnosing oral precancer and cancer

The early diagnosis of oral precancer and cancer is crucial and could have the highest impact on improving survival rates. A meta-analysis was conducted to compare the accuracy between the OralCDx brush biopsy and DNA-image cytometry in diagnosing both conditions. Bibliographic databases were systematically searched for original relevant studies on the early diagnosis of oral precancer and oral cancer. Study characteristics were evaluated to determine the accuracy of the two screening strategies. Thirteen studies (eight of OralCDx brush biopsy and five of DNA-image cytometry) were identified as having reported on 1981 oral mucosa lesions. The meta-analysis found that the area under the summary receiver operating characteristic curves of the OralCDx brush biopsy and DNA-image cytometry were 0.8879 and 0.9885, respectively. The pooled sensitivity, specificity, and diagnostic odds ratio of the OralCDx brush biopsy were 86% (95% CI 81-90), 81% (95% CI 78-85), and 20.36 (95% CI 2.72-152.67), respectively, while these modalities of DNA-image cytometry were 89% (95% CI 83-94), 99% (95% CI 97-100), and 446.08 (95% CI 73.36-2712.43), respectively. Results of a pairwise comparison between each modality demonstrated that specificity, area under the curve (AUC), and Q(∗) index of DNA-image cytometry was significantly higher than that of the OralCDx brush biopsy (Z=2.821, p<0.05; Z=1.711, p<0.05; Z=1.727, p<0.05), but no significant difference in sensitivity was found (Z=1.520, p>0.05). In conclusion, the meta-analysis of the published studies indicated that DNA-image cytometry is more accurate than the OralCDx brush biopsy in diagnosing oral precancer and oral cancer.

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

BACKGROUND

Oral squamous cell carcinoma is the most common form of malignancy of the lip and oral cavity, often being proceeded by potentially malignant disorders (PMD). Early detection can reduce the malignant transformation of PMD and can improve the survival rate for oral cancer. The current standard of scalpel biopsy with histology is painful for patients and involves a delay whilst histology is completed; other tests are available that are unobtrusive and provide immediate results.

OBJECTIVES

PRIMARY OBJECTIVE

To estimate the diagnostic accuracy of index tests for the detection of oral cancer and PMD of the lip and oral cavity, in people presenting with clinically evident lesions.

SECONDARY OBJECTIVE

To estimate the relative accuracy of the different index tests.

SEARCH METHODS

The electronic databases were searched on 30 April 2013. We searched MEDLINE (OVID) (1946 to April 2013) and four other electronic databases (the Cochrane Diagnostic Test Accuracy Studies Register, the Cochrane Oral Health Group's Trials Register, EMBASE (OVID) and MEDION (Ovid)). There were no restrictions on language in the searches of 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 PMD or oral squamous cell carcinoma of the lip or oral cavity: vital staining, 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 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

We included 41 studies, recruiting 4002 participants, in this review. These studies evaluated the diagnostic accuracy of conventional oral examination with: vital staining (14 studies), oral cytology (13 studies), light-based detection or oral spectroscopy (13 studies). Six studies assessed two combined index tests. There were no eligible diagnostic accuracy studies evaluating blood or salivary sample analysis.The summary estimates for vital staining obtained from the meta-analysis were sensitivity of 0.84 (95% CI 0.74 to 0.90) with specificity of 0.70 (0.59 to 0.79), with 14 studies were included in the meta-analysis. For cytology, sensitivity was 0.91 (0.81 to 0.96) and specificity was 0.91 (0.81 to 0.95) with 12 studies included in the meta-analysis. For light-based detection, sensitivity was 0.91 (0.77 to 0.97) and specificity was 0.58 (0.22 to 0.87) with 11 studies included in the meta-analysis. The relative test accuracy was assessed by adding covariates to the bivariate analysis, no difference in model fit was observed.

AUTHORS' CONCLUSIONS

The overall quality of the included studies was poor. None of the adjunctive tests can be recommended as a replacement for the currently used standard of a scalpel biopsy and histological assessment. Given the relatively high values of the summary estimates of sensitivity and specificity for cytology, this would appear to offer the most potential. Combined adjunctive tests involving cytology warrant further investigation.

Diagnostic modalities for squamous cell carcinoma: an extensive review of literature-considering toluidine blue as a useful adjunct

INTRODUCTION

Oral Squamous Cell Carcinomas have been considered as the most prevalent malignancies in the head and neck region and are frequently undiagnosed until symptomatic with an advanced stage of disease. So there is an urgent need to device methods for the detection of oral premalignant lesions and oral cancer at an early stage in order to improve the survival rate for patients. A number of tests have been done for the detection of oral cancer which include oral brush biopsy, the Vizilite, oral autofluorescence including chemiluscence, photodynamic detection, toluidine blue staining, methylene blue staining, incisional biopsy and many more.

MATERIAL

The article reviews various diagnostic modalities available at present for detection of squamous cell carcinomas and oral epithelial dysplasias based on advanced PUBMED search of the English language literature from the year 1972 to present in order to help us select the most suitable among them fulfilling the desired criteria of being non-invasive, highly specific and sensitive, economically viable, having a scope to be used for mass screening, easy to process, having low inter examiner variability and possibly not requiring high expertise to conduct and interpret the results.

CONCLUSION

After reviewing various diagnostic modalities, we conclude that toluidine blue staining emerges as a clear winner among all these and it can act as a valuable adjunct to incisional biopsy in detection of oral cancer and may not substitute it except in certain circumstances when its results are carefully correlated with the patient history and clinical characteristics of the mucosal disorder, considering the fact that incisional biopsy has been reported to cause dissemination of cancer cells in the circulation there by increasing the possibility of metastasis. We must emphasize that toludine blue is a screening modality and not a diagnostic procedure like biopsy and hence cannot replace a confirmatory biopsy as a whole.

Adjunctive diagnostic techniques for oral lesions of unknown malignant potential: Systematic review with meta-analysis

BACKGROUND

The purpose of this study was to critically review the published evidence concerning adjunctive diagnostic techniques in the diagnosis of oral lesions of unknown malignant potential.

METHODS

We conducted a systematic literature review with meta-analysis using PubMed to search for articles published from June 1993 through June 2013 to identify prospective studies evaluating any diagnostic method, with tissue biopsy confirmation, in clinically evident oral lesions of unknown malignant potential. Aggregate weighted totals and SEs for true, false-positive, false-negative, and inadequate results were calculated and compared among subgroups.

RESULTS

Forty-eight articles satisfying inclusion criteria were identified. Twenty-five were included in quantitative synthesis.

CONCLUSION

Oral cytology holds higher diagnostic value than specialist's oral examination, which holds higher value than in vivo toluidine blue staining. This study does not support the use of computer-aided or liquid-based cytology. Future studies should be designed to test multiple methods in the same patient population to allow direct comparison among various techniques.

Transepithelial Brush Biopsy - Oral CDx® - A Noninvasive Method for the Early Detection of Precancerous and Cancerous Lesions

INTRODUCTION

The Oral CDx® brush biopsy (BB) method is a computer-assisted sample analysis that detects abnormal cells in all cell layers of the epithelium of the oral mucosa.

METHOD

We took 263 oral BBs from 200 patients with potentially malignant disorders.

RESULTS

We received 204 negative results and 39 atypical, 7 positive and 13 inadequate results. SBs were taken in 56 cases. Therefore, the sensitivity for the detection of abnormal cells was 90% and the specificity was 44.1%. The positive predictive value accounted for 47.2% and the NPV accounted for 88.2%.

DISCUSSION AND CONCLUSION

For the results of sensitivity and specificity of the Oral CDx® BB, there is still space for improvement but they are already high. Additional methods like DNA-image cytometry may enhance the results. But it is a simple and noninvasive method which does not need a special effort either from the patient or from the clinicians.

The use of quantitative cytology in identifying high-risk oral lesions in community practice

OBJECTIVE

This study evaluated whether quantitative cytology (QC) can disclose abnormal DNA content (aneuploidy) and abnormal nuclear morphology of high-risk potentially malignant disorders (PMDs) of the oral mucosa found in the community in reference to clinicohistopathologic features.

STUDY DESIGN

A total of 171 patients at community-based clinic with suspicious oral lesions were evaluated with concurrent but independent histopathologic and QC assessments.

RESULTS

QC-positive results were associated with oral lesions with higher clinical risk factors: large size, nonhomogeneous surface texture, and located at high-risk anatomic sites. Only 3% of benign/reactive and 5% of low-risk PMDs were QC positive, while 92% of high-risk PMDs and 88% of squamous cell carcinomas (SCCs) were QC positive. The sensitivity and specificity of QC for detection of high-grade dysplasia/SCC were 89% and 97%.

CONCLUSIONS

QC could serve as an adjunctive tool for the detection of high-risk PMD/SCC requiring immediate clinical care.

How should we manage oral leukoplakia?

The aim of this article is to review the management of oral leukoplakia. The topics of interest are clinical diagnosis, methods of management and their outcome, factors associated with malignant transformation, prognosis, and clinical follow-up. Global prevalence is estimated to range from 0.5 to 3.4%. The point prevalence is estimated to be 2.6% (95% CI 1.72-2.74) with a reported rate of malignant transformation ranging from 0.13 to 17.5%. Incisional biopsy with scalpel and histopathological examination of the suspicious tissue is still the gold standard for diagnosis. A number of factors such as age, type of lesion, site and size, dysplasia, and DNA content have been associated with increased risk of malignant transformation, but no single reliable biomarker has been shown to be predictive. Various non-surgical and surgical treatments have been reported, but currently there is no consensus on the most appropriate one. Randomised controlled trials for non-surgical treatment show no evidence of effective prevention of malignant transformation and recurrence. Conventional surgery has its own limitations with respect to the size and site of the lesion but laser surgery has shown some encouraging results. There is no universal consensus on the duration or interval of follow-up of patients with the condition.

Biopsy techniques and diagnoses & treatment of mucocutaneous lesions

Oral mucosal lesions are commonly encountered in clinical practice. One study reported that they occurred in approximately 27.9% of patients aged 17 years and older and in 10.3% of children aged 2 to 17 years. The diagnosis and treatment of mucosal diseases should be an integral part of the general practitioner's practice. According to an American Dental Association survey conducted in 2007, 44% of biopsies were performed by a general practictioner. Understanding of the fundamentals of diagnosing mucocutaneous lesions requires a sound knowledge of their origin and clinical course, and of biopsy methods using contemporary diagnostic tools and techniques.

The efficacy of oral brush biopsy with computer-assisted analysis in identifying precancerous and cancerous lesions

Background

Cancer of the oral cavity is the sixth most common malignancy reported worldwide and one with the highest mortality rate among all malignancies. There is a paucity of reliable diagnostic methods to detect early malignancies. This study was performed to evaluate the sensitivity and specificity of brush biopsy in identifying oral premalignant and malignant lesions.

Methods

Oral brush and scalpel biopsies were performed on 85 consecutive patients presenting with an oral lesion deemed to be minimally suspicious by clinical examination and the results were compared.

Results

Of 79 patients with adequate brush biopsy samples with matching scalpel biopsies, 27 revealed histopathologic evidence of dysplasia or carcinoma, 26 of which were independently identified with the oral brush biopsy (sensitivity: 96.3% - 95% CI, 87%-100%). 52 oral lesions did not reveal any histopathologic evidence of dysplasia or carcinoma and of these, brush biopsy reported 47 as "negative" and 5 as "atypical"(specificity of "positive" brush biopsy result is 100%- 95% CI, 93%-100%; specificity for "atypical" brush biopsy result is 90.4%- 95% CI, 82%-97%. The positive predictive value of an abnormal oral brush biopsy was 84% and the negative predictive value was 98%.

Conclusion

Our study demonstrated that the oral brush biopsy is an accurate test in identifying oral premalignant and malignant lesions, even if minimally suspicious.

Non-computer-assisted liquid-based cytology for diagnosis of oral squamous cell carcinoma

The development of oral squamous cell carcinoma (OSCC) occasionally follows the neoplastic progression of other premalignant lesions. Although biopsy is the definitive diagnostic method, liquid-based cytology is an adequate method for screening suspicious lesions. We compared liquid-based cytology to histology for diagnosis of OSCC in patients with oral lesions that raised clinical suspicion of malignancy. Our sample consisted of 48 patients. Cytological samples were obtained by scraping the lesion superficially using Cytobrush®. We conducted cytological and histopathological evaluation of all preparations. We estimated sensitivity and specificity levels as well as positive and negative predictive values. The degree of inter-observer agreement for both methods was assessed using the kappa index. Twenty-eight (58.3%) of the cases finally were diagnosed with OSCC and 20 (41.7%) were determined to be premalignant lesions. We observed eight false negatives and no false positives; OSCC prevalence was 56.5%. The values for diagnostic indices were: sensitivity, 69% (CI 95%, prevalence 51.87); specificity, 100%; positive predictive value, 100%; negative predictive value, 71% (CI 95% 54.82). A kappa index of 0.622 (CI 95% 0.93, 0.39) was observed.

Comparison of three sampling instruments, Cytobrush, Curette and OralCDx, for liquid-based cytology of the oral mucosa

Exfoliative cytology of the oral cavity is a simple and noninvasive technique that permits the study of epithelial cells. Liquid-based cytology is an auxiliary diagnostic tool for improving the specificity and sensitivity of conventional cytology. The objective of our study was to compare the quality of normal oral mucosa cytology samples obtained using three different instruments, Cytobrush®, dermatological curette and Oral CDx® for liquid-based cytology. One hundred four cytological samples of oral cavity were analyzed. Samples were obtained from healthy volunteer subjects using all three instruments. The clinical and demographic variables were age, sex and smoking habits. We analyzed cellularity, quality of the preparation and types of cells in the samples. All preparations showed appropriate preparation quality. In all smears analyzed, cells were distributed uniformly and showed no mucus, bleeding, inflammatory exudate or artifacts. We found no correlation between the average number of cells and the type of instrument. The samples generally consisted of two types of cells: superficial and intermediate. No differences were found among the cytological preparations of these three instruments. We did not observe basal cells in any of the samples analyzed.

Techniques for precancerous lesion diagnosis

The development of the oral squamous cell carcinoma (OSCC) is a multistep process that requires the accumulation of multiple genetic alterations usually preceded by detectable mucosal changes, most often leukoplakias and erythroplakias. The clinical appearance of oral precancerous lesions and their degree of epithelium dysplasia suggests the malignization potential. Several techniques have been developed to improve the clinical and cytological diagnosis of oral precancerous lesions. The present paper reviews the main techniques used to improve premalignant lesion diagnosis.

Diagnostic clinical aids in oral cancer

Conventional oral exploration (visual and palpation examination) constitutes the current gold standard for oral cancer screening, while biopsy and histopathological examination represents the indispensable study for the detection of cases in patients with an identified lesion. Imaging techniques (DPT, CT, and MRI) are frequently used to supplement the clinical evaluation and staging of the primary tumour and regional lymph nodes. There are also a number of techniques that may contribute to the diagnosis of oral cancer: toluidine blue test has been used as a diagnostic aid for the detection of oral cancer over decades. Recently developed light-based detection systems have progressively improved in sensitivity and specificity, but multicentre controlled studies conducted by general dental practitioners must be designed in order to justify their application. The oral brush biopsy appears to overestimate dysplastic lesions and produces a high number of false-positive results. In the near future, immunological and biochemical alterations in the serum (e.g., circulating immune complexes, carcinoembryonic antigen, squamous cell carcinoma associated antigen, inhibitor of apoptosis, cytokeratin fragments, and annexin A1) as well as specific saliva analysis (e.g., cancer related cytokines, metalloproteinases, epithelial tumour markers, DNA promoter hypermethylation, and saliva micro-RNA) may become important tools for the detection of oral cancer.