Human papillomavirus genotypes and p16 expression in oral leukoplakia and squamous cell carcinoma.

Several studies have shown a broad variation in the prevalence of human papillomavirus (HPV) in oral leukoplakia (OLK) and oral squamous cell carcinoma (OSCC), whereas the relationship is less well-defined and specific HPV genotypes lack examination in OLK. In the present study, the role of HPV and surrogate p16 expression was investigated to explore the correlation and pathogenesis in OLK and OSCC. Polymerase chain reaction (PCR) and flow-through hybridization technology were utilized to detect HPV genotypes in oral exfoliated cells from 30 healthy volunteers, 103 OLK and 30 OSCC patients. Expression of p16 was assessed by immunohistochemistry (IHC) in biopsies from these OLK and OSCC, in addition to 15 normal oral mucosal tissues as the control group. The healthy controls showed 3.3% (1/30) HPV presence; In OLK and OSCC, the detection rate was 4.9% (5/103), 3.3% (1/30), respectively. No significant relationship between HPV and OLK or OSCC was observed when compared with the control group (P>0.05). All 6 HPV-positive OLK and OSCC cases had p16 overexpression. But the sensitivity of p16 IHC was poor, because 88.4% (38/43) of p16 over-expressed OLK were HPV negative. There was no statistical significance between HPV and the sex, age, site, alcohol consumption, or smoking. These findings suggested HPV had a low prevalence in OLK and OSCC. This suggests the detection of HPV genotypes by PCR in exfoliated cells combined with p16 IHC may be more accurate to represent HPV infection.

[Research progress of quantitative DNA analysis in oral carcinoma and precancerous lesions].

Normal individual cells had 23 pairs of chromosome and stable DNA content. DNA content was varied during malignant transformation, which was specific feature of tumor. Quantitative DNA analysis can reflect cellular physiological or pathological condition by nuclear DNA content, which had significant role in early diagnosis, predication of prognosis and treatment selection. This article summarized the research progress of quantitative DNA analysis in oral carcinoma and precancerous lesions in recent years.

MicroRNA-155 in oral squamous cell carcinoma: Overexpression, localization, and prognostic potential.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is a common malignancy with poor prognosis. MicroRNAs (miRNAs) play an important role in cancer, but their role in OSCC is not clarified. METHODS: We performed miRNA microarray, quantitative reverse transcription polymerase chain reaction (qRT-PCR), and fluorescence in situ hybridization (FISH) to examine miRNA expression in OSCC and paired adjacent cancer-free mucosal (ACF) tissues. RESULTS: Thirteen miRNAs, including miRNA-155, were upregulated (>2-fold) in OSCC against ACF. MiRNA-155 was confirmed to have significantly higher expression in OSCC against ACF (paired-samples t test; p = .041) and it was localized in the cancer nest, inflammatory area, and vascular endothelium of OSCC. High expression of miRNA-155 in ACF tissue was an independent prognostic indicator for OSCC survival. CONCLUSION: MiRNA-155 was overexpressed in OSCC and it was located in the cancer nest, inflammatory area, and vascular endothelium of OSCC. High miRNA-155 expression level in ACF may predict poor prognosis in patients with OSCC.

[The effect of retrovirus-mediated hTRT transfection into cultured oral keratinocytes].

PURPOSE: Human telomerase reverse transcriptase (hTRT) was transfected into cultured oral keratinocytes (OKC) mediated by pBABE-tert recombined retrovirus to investigate the effect on OKC lifespan. METHODS: pBABE-tert recombined retrovirus loaded with hTRT gene was amplified by transfected PT67 cells, and then transfected into cultured OKC in vitro. The positive clones of OKC were separated by puromycin and subcultured. Telomerase activity was analyzed by telomerase PCR-ELISA and PCR-PAGE. RESULTS: The hTRT positive clones of OKC showed telomerase expression, with extending lifespan to 8-9 passages. CONCLUSIONS: The hTRT transfected OKC can prolong doubly lifespan but not be immortalized, which indicates that cellular immortality mechanism is complicated and multi-controled. Telomerase activity is the key for cell immortalization but not the only impact factor.

Phospholipase C-γ1 expression correlated with cancer progression of potentially malignant oral lesions.

BACKGROUND: Phospholipase C-γ1 (PLCγ1) is required for cellular migration during tumor progression and invasion of oral squamous cell carcinoma (OSCC) cells. The objective of the current study was to determine immunoexpression pattern of PLCγ1 in oral potentially malignant lesions (OPLs) and evaluate PLCγ1 usefulness as a biomarker for predicting clinical behavior in the carcinogenesis of OPL. METHODS: In a retrospective follow-up study, the expression pattern of PLCγ1 protein was determined using immunohistochemistry in samples from 68 patients, including untransformed cases (n = 38) and malignant-transformed cases (n = 30). The corresponding post-malignant lesions (OSCCs) were also performed. RESULTS: We observed that elevated expression of PLCγ1 in 40 of 68 (59%) general OPLs and 23 of 30 (77%) OSCCs compared with that in normal oral mucosa. Kaplan-Meier analysis revealed that patients with PLCγ1 positivity had a significantly higher incidence of OSCC than those with PLCγ1 negativity. Cox regression analysis revealed that PLCγ1 expression patterns were significantly associated with increased risk of malignant progression. In addition, the correlation between PLCγ1 expression in pre-malignant OPL and that in post-malignant OSCC was significant (P = 0.004). CONCLUSION: These data indicate that PLCγ1 expression in OPL correlated with oral cancer progression, and PLCγ1 may serve as a useful marker for the identification of high-risk OPL into OSCC.

Expression of cancer stem cell markers ALDH1 and Bmi1 in oral erythroplakia and the risk of oral cancer.

BACKGROUND: Oral erythroplakia (OE) is a notoriously aggressive oral pre-malignant lesion with a high tendency to oral cancer development, but its biological behavior is largely unknown. The objective of this study was to determine the expression of cancer stem cell markers ALDH1 and Bmi1 in OE and their correlation with malignant transformation of OE. METHODS: In a retrospective case-control study, expression patterns of ALDH1 and Bmi1 were determined using immunohistochemistry in samples from 34 patients with OE, including patients with untransformed lesions (n=17) and patients with malignant transformed lesions (n=17). RESULTS: ALDH1 and Bmi1 expression was observed in 19 (55.9%) and 20 (58.8%) of 34 patients with OE, respectively. Multivariate analysis revealed that ALDH1 expression was significantly associated with increased risk of transformation (P<0.05), but Bmi1 expression was not a significant marker (P > 0.05). Notably, the coexpression of both ALDH1 and Bmi1 was a strong indicator associated with 8.56-fold (95% confidence interval [CI], 1.74-42.17; P<0.01) for malignant transformation. Point prevalence analysis revealed that 78.6% (95% CI, 54.0-100) of the patient with coexpression of both ALDH1 and Bmi1 developed oral cancer. CONCLUSION: Our data indicated that the expression patterns of ALDH1 and Bmi1 in OE were associated with malignant transformation, suggesting that they may be valuable predictors for evaluating the risk of oral cancer.

Expression patterns of cancer stem cell markers ALDH1 and CD133 correlate with a high risk of malignant transformation of oral leukoplakia.

Molecular markers for predicting oral cancer development in premalignant oral leukoplakia (OL) are urgently needed. The objective of this study was to examine the expression patterns of cancer stem cell markers ALDH1 and CD133 in samples from patients with OL, and determine their prognostic values for subsequent development of oral cancer. Immunohistochemistry for ALDH1 and CD133 was performed in samples from a cohort of 141 patients with biopsy-proven OL who received a mean follow-up of 5.5 years. Patient clinicopathologic and follow-up data were analyzed. Expression of ALDH1 and CD133 was observed in 54 (38.3%) and 32 (22.7%) of 141 patients with OL, respectively. Kaplan-Meier analysis showed that 48.1% patients with ALDH1-positivity developed oral cancer compared with 12.6% those with ALDH1-negativity (p < 0.001). Meanwhile, 59.4% patients with CD133-positivity developed oral cancer compared with 16.5% those with CD133-negativity (p < 0.001). Multivariate analysis revealed that ALDH1 and CD133 expression was associated with 4.17-fold [95% confidence interval (CI), 1.96-8.90; p < 0.001] and 2.86-fold (95% CI, 1.48-5.55; p = 0.002) increased risk of OL transformation, respectively. Collectively, these data demonstrated for the first time that the expression of ALDH1 and CD133 correlated with malignant transformation in a large series of patients with OL who received a long-term follow-up, which suggests that they may serve as predictors to identify OL with a high risk of oral cancer development.

A retrospective clinicopathological study on oral lichen planus and malignant transformation: Analysis of 518 cases

Objective: To investigate the epidemiological and clinical characteristics of a relatively large cohort of patients with oral lichen planus (OLP) from eastern China. Study design: A total of 518 patients with histologically confirmed OLP in a long-term follow-up period (6 months-21.5 years) were retrospectively reviewed in our clinic. Results: Of the 518 patients, 353 females and 165 males were identified. The average age at diagnosis was 46.3 years (range 9-81 years) with the buccal mucosa being the most common site (87.8%). At initial presentation, white lichen and red lichen was seen in 52.3% and 47.7% patients, respectively. Of these, 5 (0.96%) patients previously diagnosed clinically and histopathologically as OLP developed oral cancer. All of them were the females with no a history of smoking or alcohol use. Conclusions: Clinical features of eastern Chinese OLP patients were elucidated. Notably, approximately 1% of OLP developed into cancer, which provides further evidence of potentially malignant nature of OLP (AU)

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Upregulation of miR-31* is negatively associated with recurrent/newly formed oral leukoplakia.

BACKGROUND: Oral leukoplakia (OLK) is a potentially malignant disorder of the oral cavity. However, the underlying mechanism of OLK is still unclear. In this study, we explore possible miRNAs involved in OLK. METHODOLOGY/PRINCIPAL FINDINGS: Using miRNA microarrays, we profiled miRNA expression in OLK and malignantly transformed OLK (mtOLK) tissue samples. The upregulation of miR-31*, miR-142-5p, miR-33a, miR-1259, miR-146b-5p, miR-886-3p, miR-886-5p, miR-519d, and miR-301a along with the downregulation of miR-572, miR-611, miR-602, miR-675, miR-585, miR-623, miR-637, and miR-1184 in mtOLK were new observations. Fluorescence in situ hybridization (FISH) analyses confirmed that miR-31* is highly expressed in mtOLK. There was a significant difference between the FISH score (p<0.05) in patients with or without recurrent/newly formed OLK. Functional analyses demonstrated that a miR-31* inhibitor decreased apoptosis in the Leuk-1, which is an immortalized oral epithelial cell line spontaneously derived from an oral leukoplakia lesion. miR-31* regulated apoptosis, cell proliferation, migration, and invasion in the HOIEC, which is a HPV E6/E7-immortalized oral epithelial cell line. Furthermore, miR-31* modulated the biological functions of apoptosis, cell proliferation, cell cycle, migration, and invasion in the oral squamous cell carcinoma cell line, Cal-27. Using bioinformatic analyses and dual luciferase reporter assays, we determined that the 3' untranslated region of fibroblast growth factor 3 (FGF3) is the target of miR-31*. Expression of FGF3 was downregulated or upregulated in the presence of a miR-31* mimic or inhibitor, respectively. CONCLUSIONS/SIGNIFICANCE: Upregulation of miR-31* is negatively associated with recurrent/newly formed OLK. MiR-31* may exert similar but distinguishable effects on biological function in oral cells with different malignant potential. FGF3 is the target of miR-31*. miR-31* may play an important role during OLK progression through regulating FGF3. MiRNA* strands may also have prominent roles in oral carcinogenesis.

A retrospective clinicopathological study on oral lichen planus and malignant transformation: analysis of 518 cases.

OBJECTIVE: To investigate the epidemiological and clinical characteristics of a relatively large cohort of patients with oral lichen planus (OLP) from eastern China. STUDY DESIGN: A total of 518 patients with histologically confirmed OLP in a long-term follow-up period (6 months-21.5 years) were retrospectively reviewed in our clinic. RESULTS: Of the 518 patients, 353 females and 165 males were identified. The average age at diagnosis was 46.3 years (range 9-81 years) with the buccal mucosa being the most common site (87.8%). At initial presentation, white lichen and red lichen was seen in 52.3% and 47.7% patients, respectively. Of these, 5 (0.96%) patients previously diagnosed clinically and histopathologically as OLP developed oral cancer. All of them were the females with no a history of smoking or alcohol use. CONCLUSIONS: Clinical features of eastern Chinese OLP patients were elucidated. Notably, approximately 1% of OLP developed into cancer, which provides further evidence of potentially malignant nature of OLP.

Expression of podoplanin and ABCG2 in oral erythroplakia correlate with oral cancer development.

Oral erythroplakia (OE) is a notoriously aggressive oral premalignant lesion with a high tendency to oral cancer development, but it's biological behavior is largely unknown. The objective of the current study was to determine podoplanin and ABCG2 immunoexpression in OE and both correlation to malignant transformation of OE. In a retrospective follow-up study, the expression patterns of podoplanin and ABCG2 were determined using immunohistochemistry in samples from 34 patients with OE, including patients with untransformed lesions (n=17) and patients with malignant transformed lesions (n=17). Podoplanin and ABCG2 expression was observed in 15 (44.1%) and 21 (61.8%) of 34 patients, respectively. Multivariate analysis revealed that podoplanin and ABCG2 expression was associated with 6.31-fold (95% confidence interval [CI], 1.02-38.92; P=0.047) and 14.39-fold (95% CI, 2.02-102.29; P=0.008) increased the risk of transformation, respectively. Point prevalence analysis revealed that 90.9% (95% CI, 70.7-100) of the patient with both podoplanin and ABCG2 positivity developed oral cancer. Collectively, our data indicated that the expression patterns of podoplanin and ABCG2 in OE were associated with oral cancer development, suggesting that podoplanin and ABCG2 may be valuable predictors for evaluating oral cancer risk.

Oral cancer development in patients with leukoplakia--clinicopathological factors affecting outcome.

BACKGROUND: Oral leukoplakia (OL) is the best-known potentially malignant disorder. The objective of the current study was to evaluate the clinicopathological factors predictive of outcome in a large cohort of patients with OL, and report our experience in the early detection of malignant events. METHODS: A total of 320 patients with biopsy-proven OL were retrospectively reviewed from the study institution who had a mean follow-up of 5.1 years. Data on patient and lesion at initial diagnosis and patient underwent sequential biopsies were reviewed. Multiple biopsies indicates > = 3 times sequential biopsies. Oral cancer-free survival rate (OCFS) was determined by the Kaplan-Meier method and significant factors were identified by Cox regression analysis. RESULTS: The 3-year and 5-year OCFS was 86.6% and 82.0%, respectively. A new binary system of grading oral dysplasia was performed and Kaplan-Meier analysis indicated that high-grade dysplasia had significantly higher malignant incidence than low-grade dysplasia (5-year OCFS, 90.5% vs 59.0%; P<0.001), especially during the first 2-3 years of follow-up. Multivariate analysis revealed that the 4 factors including patient aged >60 years, lesion located at lateral/ventral tongue, non-homogenous lesion, high-grade dysplasia were independent significant indicators for OL malignant transformation. In addition, significant positive correlation between the multiple biopsies and these 4 factors and malignant outcome was established. CONCLUSIONS: Elderly patients with OL located at lateral/ventral tongue and who had non-homogenous lesion with high-grade dysplasia correlated much higher risk of transformation. This high-risk subpopulation was suggested to undergo sequential biopsies and histologic examination contributing to early detection of malignant event.

Phosphorylated p120-catenin expression has predictive value for oral cancer progression.

AIMS: Recent studies have shown that phosphorylation of p120-catenin (p120) promotes progression and invasion of oral squamous cell carcinoma (OSCC) cells. The objective of the current study was to evaluate the usefulness of phosphorylated p120-catenin (pp120) as a biomarker for predicting clinical behaviour in the carcinogenesis of potentially malignant oral lesions. METHODS: In a retrospective follow-up study, the expression pattern of pp120 protein was determined using immunohistochemistry in samples from 68 patients with potentially malignant oral lesions, including patients with untransformed lesions (n=38) and patients with malignant transformed lesions (n=30). Analysis of corresponding post-malignant lesions (OSCCs) was also performed. RESULTS: There was high expression of pp120 in 35 of 68 (51.5%) of general potentially malignant oral lesions and 23 of 30 (76.7%) of OSCCs compared with expression in normal oral mucosa. Kaplan-Meier analysis revealed that patients with potentially malignant oral lesions expressing high levels of membranous pp120 had a significantly higher incidence of OSCC than those expressing low expressing pp120 (p=0.002; log-rank test). Cox regression analysis revealed that this pp120 expression pattern was significantly associated with a 3.43-fold increase in the risk of malignant progression (p=0.007). In addition, there was a significant correlation between high levels of membranous expression of pp120 in pre-malignant lesions and cytoplasmic expression in post-malignant lesions (p=0.028). CONCLUSIONS: The data indicated that a high level of membranous expression of pp120 in potentially malignant oral lesions is an early event during oral carcinogenesis, and that the mislocalisation of expression of pp120 from the cell membrane to the cytoplasm is associated with oral cancer progression. pp120 may serve as a useful marker for the identification of a high risk of potentially malignant oral lesions progressing to OSCC.

DAPK promoter hypermethylation in tissues and body fluids of oral precancer patients.

Death-associated protein kinase (DAPK) has been suggested as a tumor suppressor gene. A high frequency of DAPK promoter hypermethylation has been noted in head and neck cancers and other solid tumors, and it has been used as a tumor marker in molecular detection strategies. Our aim was to examine DAPK promoter hypermethylation in tissue, blood, and salivary rinse samples of oral precancer patients (OPs) and to explore the potential role in oral carcinogenesis. DAPK hypermethylation was analyzed in 77 OPs and 32 oral squamous cell carcinomas (OSCCs) by real-time quantitative methylation-specific PCR (QMSP). We compared the hypermethylation expression between two groups and analyzed the associations with clinicopathologic parameters. The promoter hypermethylation frequency of DAPK in tissue (46.9%) and blood (52.2%) of OSCCs was significantly higher than those in OPs (19.5%, P = 0.004; 22.4%, P = 0.007, respectively). DAPK promoter hypermethylation expression in blood was correlated with its expression in tissue (r = 0.49, P < 0.000). The OP patients who smoked more than 20 years were found 40.0% tissue DAPK hypermethylation in contrast with 10.7% tissue DAPK hypermethylation in the patients whose smoking duration ≦20 years (P = 0.010). Our results suggest that DAPK hypermethylation is an early event in oral carcinogenesis and blood DAPK hypermethylation might be a potential minimal invasive biomarker for OSCC early detection.

Two stem cell markers, ATP-binding cassette, G2 subfamily (ABCG2) and BMI-1, predict the transformation of oral leukoplakia to cancer: a long-term follow-up study.

BACKGROUND: Although oral leukoplakia (OL) is the best-known potentially malignant disorder, the risk of OL malignant transformation is difficult to assess. ATP-binding cassette, G2 subfamily (ABCG2) and BMI-1 are stem cell markers that have been found to be associated with head and neck tumorigenesis. The objective of the current study was to evaluate the usefulness of ABCG2 and BMI-1 in predicting OL transformation. METHODS: In a retrospective cohort of 135 patients with OL from the study institution who had a mean follow-up of 5.5 years, 32 developed cancer between 1985 and 2008. The expression of ABCG2 and BMI-1 was determined using immunohistochemistry in samples from these patients, and included untransformed OL (n = 103) and malignant-transformed OL (n = 32). The association between protein expression and clinicopathological parameters and transformation was analyzed. RESULTS: Expression of ABCG2 and BMI-1 was observed in 58 (43.0%) and 44 (32.6%) of 135 patients, respectively. The correlation between ABCG2 and BMI-1 expression was significant (P = .024). Kaplan-Meier analysis revealed that 37.9% of patients with ABCG2 positivity developed cancer compared with 13.0% of patients with ABCG2 negativity (P = .014, log-rank test). Approximately 40.9% of patients with BMI-1 positivity developed cancer compared with 15.4% of patients with BMI-1 negativity (P = .029, log-rank test). Multivariate analysis revealed that ABCG2 and BMI-1 expression was associated with a 3.24-fold (95% confidence interval [95% CI], 1.31-7.98; P = .011) and 4.03-fold (95% CI, 1.59-10.26; P = .003) increased the risk of transformation, respectively. CONCLUSIONS: ABCG2 and BMI-1 expression was found to be associated with the development of oral cancer in a large cohort of patients with OL for whom long-term follow-up was available, which suggests that ABCG2 and BMI-1 may be used as predictors of OL transformation.

A clinicopathological study on verrucous hyperplasia and verrucous carcinoma of the oral mucosa.

BACKGROUND: Oral verrucous hyperplasia (VH) and verrucous carcinoma (VC) are two clinicopathologically distinctive oral verrucous lesions. The objective of this study was to investigate the clinicopathological features of the two verrucous lesions and estimate their relationship from China. METHODS: Retrospective review of two series of patients with histologically confirmed VH (n = 121) and VC (n = 56) between 1996 and 2009 in our hospital were conducted. RESULTS: The average age of VH was 58.5 years (ratio male:female = 1.37) with the tongue being the predominant site. The average age of VC was 64.3 years (ratio male:female = 1.15) with the lower lip being the predominant site. Multivariate analysis revealed that the elderly patient with verrucous lesion (≥60 years) was associated with 3.06-fold (P = 0.007) increased carcinoma risk compared with the non-elderly patient. The lesion located on lower lip was associated with 13.54-fold (P < 0.001) increased carcinoma risk compared with other sites. CONCLUSION: Clinicopathological features of VH and VC in China were elucidated. Elderly patient with oral verrucous lesion located on the lower lip correlates with higher risk of carcinoma.

Malignant transformation of oral epithelial dysplasia: clinicopathological risk factors and outcome analysis in a retrospective cohort of 138 cases.

AIMS: To explore the usefulness of a new binary system of grading dysplasia proposed by the World Health Organization and to identify significant risk factors for malignant transformation in a long-term follow-up cohort of patients with oral epithelial dysplasia. METHODS AND RESULTS: A total of 138 patients with histologically confirmed oral dysplasia between 1978 and 2008 were reviewed retrospectively in our department. The mean follow-up period was 5.1 years. Of these dysplasias, 37 (26.8%) developed into cancer, with a mean duration of 4.6 years. Cox regression analysis revealed that high-grade dysplasia was an independent risk factor for transition, but age, gender, lesion site, diet habit, smoking and alcohol intake were not risk factors. High-grade dysplasia was associated with a 2.78-fold (95% confidence interval 1.44-5.38; P = 0.002) increased risk of transition, as compared with low-grade dysplasia. Consistently, high-grade dysplasia had a significantly higher incidence of malignancy than low-grade dysplasia by Kaplan-Meier analysis (log-rank test, P = 0.001). CONCLUSIONS: The utilization of high-grade dysplasia as a significant indicator for evaluating malignant transformation risk in patients with potentially malignant lesions is suggested; this may be helpful to guide treatment selection in clinical practice.

Malignant potential of oral and labial chronic discoid lupus erythematosus: a clinicopathological study of 87 cases.

AIMS: To investigate clinicopathological features and identify clinicopathological risk factors for the malignant transformation of oral and labial chronic discoid lupus erythematosus (DLE) in a relatively large number of patients from China. METHODS AND RESULTS: A total of 87 patients with clinical and histopathological diagnosis of DLE between 1993 and 2009 were reviewed retrospectively in our hospital. The average age at diagnosis was 51.7 years, with a male:female ratio of 1:1.8. The lower lip was the most common site (71.3%). We documented six DLE patients with malignant transformation. On univariate analysis, patients with high-risk dysplasia (P = 0.002) or aged >60 (P = 0.045) were associated with DLE malignant transformation, but gender, lesion site, smoking and alcohol intake were not risk factors. On multivariate analysis, high-risk dysplasia was a significant indicator for DLE malignant transformation. High-risk dysplasia was associated with a 14.24-fold [95% confidence interval (95% CI), 1.97-102.88; P = 0.008] increased risk of malignant transformation, compared with non/low-risk dysplasia. CONCLUSIONS: The utilization of high-risk dysplasia as a significant indicator for evaluating malignant transformation risk in patients with DLE is suggested, which may be helpful to guide treatment selection.

Squamous cell carcinoma development in previously diagnosed oral lichen planus: de novo or transformation?

OBJECTIVES: The objectives of this study were to investigate the incidence of oral squamous cell carcinoma (OSCC) developing in lesions that were previously diagnosed as oral lichen planus (OLP), and to evaluate potential contributing factors that might be associated with an increased risk for the development of OSCC in these patients. STUDY DESIGN: We retrospectively reviewed a relatively large cohort of 518 patients with OLP who received long-term follow-up (range, 6 months-21.5 years). RESULTS: There were 353 females and 165 males. Of these, 5 (0.96%) patients developed OSCC with a mean duration of 70 months. All were females with no history of smoking or alcohol use. Four of them received corticosteroid therapy. Notably, 1 of these patients received systemic corticosteroid therapy 13 months before transformation, and died of metastatic disease 46 months after transformation. CONCLUSIONS: The incidence of OSCC developing in lesions previously diagnosed as OLP is less than 1%, and females were more commonly affected. These cases appear to represent the transformation of OLP into OSCC, however it cannot be entirely ruled out that these cases may represent de novo OSCC.