Several studies have demonstrated that socioeconomic status influences the development of OPMDs and OED, and the higher the socioeconomic status, the lower the risk of these conditions [13, 19–22]. A large population survey conducted in Taiwan showed a strong correlation between low education status and betel nut use habits, which may be explained by the labouring work in Taiwan that has a cultural tradition of betel nut chewing. Moreover, the Taiwan study revealed that 25% of individuals with junior high school status were current betel chewers [23, 24] This finding is similar to our result of overall dysplasia as we also showed that junior high school education status and current betel chewing were associated with a high risk of OED. Another study in Taiwan reported a 16.5% prevalence of OED among betel quid chewers  Additionally, a hospital-based study revealed an OR of 8.5 (95% CI: 4.4–16.2) for the development of oral malignancy among current betel quid chewers with low education status . Moreover, another study in Taiwan revealed an OR of 1.27 (OR=1.27, 95% CI: 0.93–1.75) for the development of OED among current betel chewers compared with non-chewers . Furthermore, a case-control study reported an adjusted OR of 17.43 (95% Cl: 1.94–156.27) for the occurrence of leucoplakia due to betel nut chewing and smoking . All of the above studies raised concerns about the increasing risk of malignant transformation in current betel chewers. Our present study also showed a high risk of developing moderate/high-grade dysplasia among those in the high-risk group (low educational status and current betel chewing).
Initiated in 1985, TNOMSP gradually scaled up to the national level and targeted the high-risk group . High-risk individuals may be defined as tobacco users and betel chewers [27–29]. Approximately 90% of mortality resulting from oral malignancy in Southeast Asia occurs among individuals with para-habits, underscoring the need for efficient resource allocation to the high-risk group. Moreover, oral cancer is one of the leading causes of death in adolescent males in Taiwan, with the overall 5-year survival rates for I–IV stages of oral cancer reducing from 70–10% . Therefore, early prevention and correct diagnosis of OPMDs are needed to improve the patients’ outcomes.
Most OPMDs are asymptomatic and are rarely noticed by the patients, which is also evident in our present study as 85.1% of the participants were not aware of the lesion. The global prevalence of OPMDs is approximately 4.47% and is considered to be higher among Asian males . Male predominance was also observed in our study. OPMDs mainly occur on the buccal mucosa, gingiva, tongue, and floor of the mouth [33–35]. Similar findings were reported in this study, with a majority of the lesions occurring on the buccal mucosa, followed by mandibular gingiva and tongue. Our study findings are also comparable to those of a recent large population-based study conducted in southern Taiwan . Regarding the type of OPMDs in our study, erythroleucoplakia (17.2%) was the most common, followed by thin homogeneous leucoplakia (15.7%). When all types of leucoplakia, including non-homogeneous, thick, and thin homogenous leucoplakia, were included in the same group, the prevalence was 24.6%, and this finding is comparable to that of another large population study conducted in Taiwan .
Histopathological diagnosis is necessary for clinical staging of early pathologic changes in OED and helps evaluate the potential for malignant transformation. The OED malignancy transformation rate varies from 0.13–34.30% [36, 34, 37]. The standard grading system of OED, according to the World Health Organization guidelines, is mild, moderate, and high . For high-grade dysplasia, the transformation rate varies from 7–50% . In contrast, moderate dysplasia has a malignant transformation potential of 3–15%, whereas mild epithelial dysplasia has a low-risk potential (<5%) [40, 41]. However, due to the subjective grading of dysplasia, a binary grading system is encouraged following pathological research [42, 8, 38]. In our present study, we categorised our cases into mild or moderate/high-grade dysplasia based on our current practices. Individuals with moderate/high-grade dysplasia undergo surgical excision of the lesions, which is consistent with the results of a previous meta-analysis . For mild dysplasia, a follow-up system is recommended, and the patient can undergo less invasive interventions, including cryotherapy, chemoprevention, and photodynamic therapy, which have shown promising results in preventing the malignant transformation of OED [44, 45].
The major strength of this study is that it was based on the current setting of oral mucosal screening designed by the Taiwan government as TNOMSP. In addition, screening for OPMD in high-risk individuals was performed by a certified clinical practitioner. However, this study had several limitations. First, TNOMSP focuses on the high-risk individuals aged 20 years and above; thus, the underage individuals with para-habits need further investigation. Second, the principle design of TNOMSP excludes the general population with oral mucosal lesions. Therefore, a large-scale investigation and comparison of individuals with para-habits and the general population should be considered in future research.