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The objective was to assess the global oral lichen planus prevalence. We searched PubMed, EMBASE, Web of Science, and Scopus for studies published before September 2019. We evaluated the quality of studies and carried out several meta‐analyses. The global pooled prevalence was 1.01%, with a marked geographical difference (p <.001). The highest prevalence was reported from Europe (1.43%) and the lowest in India (0.49%), where tobacco‐associated keratosis appears to mask oral lichen planus resulting in attenuation of its prevalence. From the age of 40 years, the prevalence increases significantly and progressively (OR = 3.43, 95% CI = 2.48–4.73, p <.001). Studies that define diagnostic criteria report a higher prevalence (1.31% vs. 0.70%, p =.03), although the application of the WHO criteria (year 1978‐2007) does not increase the ability to diagnose the disease compared with other criteria (p =.11). The studies performed by oral medicine/oral pathology specialists report significantly higher prevalence (1.80%) than dentists (0.61%) and dermatologists (0.33%; p <.001). In conclusion, we propose that reliable diagnostic criteria should be defined, which should include a set of essential criteria including the presence of white reticular lesions in any location of the oral mucosa. The impact of histopathological confirmation with defined diagnostic criteria must be researched in the future, although its main use should be to determine the presence or absence of epithelial dysplasia. The necessity to improve the knowledge of oral lichen planus among dentists and dermatologists through continuing education is apparent in the results of this meta‐analysis. [ABSTRACT FROM AUTHOR]

Background: To evaluate published evidence on the predictive value of CCND1 amplification/cyclin D1 overexpression as malignant transformation risk markers in potentially malignant disorders (PMDs) of the head and neck. Material and Methods: We searched PubMed, Embase, Web of Science, and Scopus for studies published before June 2018. We conducted a meta‐analysis to quantify the impact of CCND1/cyclin D1 amplification/overexpression on malignant transformation of head and neck PMDs. Results: Nine studies met inclusion criteria. Quantitative evaluation indicated strong statistically significant association between CCND1/cyclin D1 amplification/overexpression and the progression of head and neck PMD to head and neck squamous cell carcinoma (risk ratio [RR] = 2.04, 95% confidence interval [CI] = 1.37‐3.03, P < .001, and RR = 2.27, 95% CI = 1.32‐3.91, P = .003, respectively). We observed moderate heterogeneity among studies (I2 = 40.7%), and we cannot rule out small‐study effects such as publication bias. The oral cavity subgroup showed the strongest association between CCND1/cyclin D1 amplification/overexpression and progression to cancer. Conclusion: CCND1/cyclin D1 amplification/overexpression is important to predict the malignant transformation risk of head and neck PMDs, especially oral PMDs. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate current evidence on the malignant transformation of oral lichen planus (OLP), oral lichenoid lesions (OLLs), and oral lichenoid reactions (LRs) and to determine the variables with greatest influence on cancer development.Material and Methods: We searched PubMed, Embase, Web of Science, and Scopus for studies published before November 2018. We evaluated the quality of studies (QUIPS tool). We carried out meta-analyses to fulfill our objectives. We examined the between-study heterogeneity and small-study effects, and conducted sensitivity studies and subgroup analyses.Results: Inclusion criteria were met by 82 studies (26,742 patients. The combined malignant transformation rate was 1.14% for OLP (95% CI = 0.84-1.49), 1.88% for OLLs (95% CI = 0.15-4.95) and 1.71% for LRs (95% CI = 0.00-5.46). Subgroup analysis revealed a higher malignant transformation rate in studies when the presence of epithelial dysplasia was not an exclusion criterion (p = 0.001), when both clinical and histopathological criteria were used for diagnosis (p < 0.001), when the follow-up was at least 12 months (p = 0.048), and when there was lower risk of potential bias (p = 0.002). Malignant transformation risk factors were: tongue localization (RR = 1.82, 95% CI = 1.21-2.74, p = 0.004), presence of atrophic-erosive lesions (RR = 4.09, 95% CI = 2.40-6.98, p < 0.001), tobacco use (RR = 1.98, 95% CI = 1.28-3.05, p = 0.002), alcohol consumption (RR = 2.28, 95% CI = 1.14-4.56, p = 0.02), and hepatitis C virus infection (RR = 4.46, 95% CI = 0.98-20.22, p = 0.053).Conclusions: The malignant transformation rates of OLP, OLLs and LRs are underestimated due essentially to restrictive diagnostic criteria, inadequate follow-up periods, and/or low quality of studies. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate current evidence in relation to the prognostic and clinicopathological significance of oral squamous cell carcinomas arising in patients with oral lichen planus (OLP-OSCC).Material and Methods: We searched PubMed, Embase, Web of Science and Scopus for studies published before May-2019. We evaluated the quality of studies (QUIPS tool). We carried out meta-analyses to fulfill our objective. We examined the between-study heterogeneity and small-study effects, and conducted sensitivity and subgroup analyses.Results: Inclusion criteria were met by 27 studies (10,505 patients with OLP, of whom 205 developed a total of 247 OSCCs). The combined 5-year mortality rate was 15.48% for OLP-OSCC (95%CI  =  7.34-25.19), clearly lower than the 34.70-50.00% mortality rate for conventional oral cancer communicated in previous official reports. Also, 14.67% (95%CI  =  6.34-24.81) of OLP-OSCC developed N+ status, compared to 47.00% of conventional oral carcinomas. Likewise, most of the OSCCs in the study were T1/T2 (93.57%, 95%CI  =  82.20-99.88) and presented at stage I/II (81.51%, 95%CI = 68.32-92.38) at the time of diagnosis, which contrasts with 50.00% of conventional carcinomas diagnosed in stages I/II. Furthermore, most of the cases were grade I (well differentiated OSCC) (67.79%; 95%CI = 43.50-88.65), in comparison to conventional OSCCs, which present typically in grade II in 90.00% of cases. Our results also show an 11.21% of the OLP-OSCC patients in this study developed multiple tumors.Conclusions: Oral squamous cell carcinomas that developed in oral lichen planus show favorable prognostic parameters, especially with regard to the mortality rate. Around 11% of OLP-OSCC patients develop multiple tumors, which confirms that OLP can lead to field cancerization. [ABSTRACT FROM AUTHOR]