Abstract

Oral cancer remains a significant global public health challenge, with increasing incidence rates, particularly among younger populations. Despite advancements in treatment, survival outcomes continue to be poor, largely due to delayed diagnosis and limited public awareness. Early detection improves prognosis, enhances survival rates, and minimises treatment-related complications. Most oral cancers are preceded by visible premalignant lesions, making them potentially detectable through routine clinical examinations.Systematic visual and oral examinations have proven to be both practical and effective in identifying early-stage disease in asymptomatic individuals. This review explores the epidemiology and risk factors associated with oral cancer, examines current screening strategies and public health interventions, and discusses future innovations, including salivary diagnostics, artificial intelligence, and mobile health technologies, that may transform early detection and management. Emphasis is placed on the need for multidisciplinary collaboration and improved public and professional awareness to shift the diagnostic window towards earlier stages of the disease.

1. Introduction

Cancer is a complex disease characterised by the uncontrolled growth of abnormal cells, affecting various organs and posing serious health threats. Among these, head and neck cancers rank as the sixth most common globally, with significantly higher rates in South-Central Asia, where they are the third most prevalent ¹. Oral squamous cell carcinoma is the most common type within this category and is increasingly recognised as a major health concern. Oral cancer involves malignant growth in the mouth, including the lips, tongue, gums, and throat, and is associated with a five-year survival rate of only 50-60% Figure 1. Alarmingly, approximately 60% of cases are diagnosed at an advanced stage ². While delays related to patients contribute significantly, diagnostic oversights by healthcare providers also play a role, underscoring the need for heightened vigilance and early detection strategies in clinical practice ^{3, 4, 5}.

The evolution of oral cancer screening has paralleled advancements in medical science, technology, and public health. Initially centred on visual inspection and palpation of oral tissues, early screening efforts had limited sensitivity for detecting lesions at an early stage. Over time, the development of adjunctive diagnostic tools, such as toluidine blue staining, brush biopsies, narrow band imaging, fluorescence visualisation, and genetic markers, has improved the ability to identify suspicious changes more accurately ⁶. Today, a multimodal approach is favoured, integrating clinical examination with diagnostic aids and individualised risk assessment. Despite these advancements, challenges remain in the widespread implementation of screening programs, particularly due to limited accessibility, provider training, and healthcare disparities in underserved communities ⁷.

The COVID-19 pandemic profoundly disrupted healthcare systems worldwide, including dental services. In the United Kingdom, the first national lockdown prompted the suspension of routine dental care in March 2020, limiting dental practices to remote consultations and triaging. Although face-to-face dental services resumed in June 2020, the 76-day interruption led to an estimated 19 million missed appointments, as reported by the British Dental Association. Even after reopening, stringent operating protocols restricted practices to reduced capacity, often around 20%, resulting in significant delays for patients. This widespread disruption, compounded by decreased general medical consultations, contributed to a decline in early oral cancer detection. A reported 65% reduction in oral cancer referrals during lockdown raises serious concerns about delayed diagnoses and potentially increased mortality. This also underscores the importance of dentists in oral cancer screening, highlighting the critical need for resilient and accessible screening systems during times of crisis ^{8, 9}.

2. Epidemiology of Oral Cancer

According to GLOBOCAN data, approximately 377,713 new cases of oral cancer were reported globally, resulting in around 177,757 deaths. The majority of these cases, nearly 65.8% (248,360 cases), occurred in Asia, followed by Europe (17.3%), North America (7.3%), the Caribbean (4.7%), and Africa (3.8%). Mortality patterns showed similar trends, with Asia accounting for the highest proportion of oral cancer deaths (74%), followed by Europe (13.8%), Africa (4.6%), the Caribbean (4.2%), and North America (2.8%). These regional disparities emphasise the need to address localised risk factors and healthcare challenges ^{10, 11}.

India, in particular, bears a significant burden of oral cancer, driven by sociocultural practices, geographic variation, and widespread use of tobacco and related substances. Among Indian men, oral cancer is the most commonly diagnosed malignancy, while among women, it ranks third. Each year, India reports approximately 77,000 new cases and 52,000 deaths from oral cancer, accounting for nearly one-fourth of the global burden ^{12, 13}.

Although oral cancer is predominantly observed in older individuals, typically between 50 and 70 years of age, it can also develop in much younger populations, including children as young as 10 years. Some institutional studies from India have documented that the incidence of oral cancer is 2 to 4 times higher in males compared to females. However, contrasting data from other studies indicate a reversal in this trend, particularly in India and Thailand, where the male-to-female ratios are reported as 1:2 and 1:156, respectively. This shift may be attributed to the rising prevalence of tobacco use among women, especially in smoked forms, which marks a significant change from past patterns. In the Indian subcontinent, the buccal mucosa and gingiva are the most commonly affected sites of oral squamous cell carcinoma (OSCC), a pattern likely linked to the habitual placement of smokeless tobacco in the buccal vestibule ¹⁴.

In America, around 47,000 new cases of oral squamous cell carcinoma (OSCC) are reported each year, accounting for roughly 1.2% of all cancers. OSCC is more prevalent in men, constituting 3% of male cancers and 2% in females, with a male-to-female ratio of approximately 2.5:1. The risk escalates with age, particularly in men over 65, where white males show higher incidence rates than black males. In younger men, both groups exhibit similar rates ^{15, 16}.

Socioeconomic factors and unequal access to healthcare may explain some of these disparities. While the overall incidence in black populations is decreasing by about 2% annually, HPV-related oral cancers are rising among white populations by over 1% each year. Interestingly, young females may have equal or slightly higher rates of oral cancer than males in the same age group ^{17, 18}.

Despite an overall decline in incidence and mortality over the decades, recent short-term data suggest a possible reversal of this trend. According to GLOBOCAN 2018, oral cancer is the 19th most common cancer in the Americas, with a 5-year prevalence of over 144,000 cases. In 2019, nearly 53,000 Americans were expected to be diagnosed, leading to about 10,800 deaths, with a 5-year survival rate of 57% ¹⁹.

3. Risk Factors

Oral cancer is largely preventable, with modifiable lifestyle choices playing a pivotal role in its development. The most prominent risk factors are the use of tobacco products and excessive alcohol intake, which collectively contribute to a significant majority of cases, estimated to be as high as 90% ²⁰. Therefore, assessing an individual’s risk based on these and other contributing elements should be an integral component of routine dental evaluations. This risk assessment not only aids in early detection but also informs personalized recall intervals and preventive strategies, similar to those used for managing dental caries, periodontal disease, and tooth wear.

The prevalence and type of risk factors can vary considerably across different regions. In Western countries, cigarette smoking and alcohol consumption are the predominant contributors to oral cancer. In contrast, in South Asian and Pacific populations, the habitual use of betel nut (areca nut), often in combination with tobacco, is a major etiological factor. Additionally, infection with high-risk strains of the human papillomavirus (HPV), particularly HPV-16, has emerged as a significant cause of oropharyngeal and oral cancers in recent years ^{21, 22}.

Key Risk Factors for Oral Cancer Figure 2:

• Tobacco Use: The most significant risk factor, responsible for nearly two-thirds of cases. This includes both smoking and smokeless forms like gutka, supari, and betel quid.

• Alcohol Consumption: Linked to about one-third of oral cancer cases.

• Human Papillomavirus (HPV): Associated with 73–75% of oropharyngeal cancers.

• Age and Gender: As people age, the cumulative exposure to risk factors and potential cellular damage increases, especially in males.

• Sun Exposure: Ultraviolet radiation can damage DNA, particularly affecting the lips.

• Poor Diet: A lack of fresh fruits and vegetables may increase susceptibility ^{23, 24, 25}.

4. Oral Cancer Screening

Oral cancer screening is a preventive approach to detect early signs of cancer or potentially malignant disorders in the mouth. It is not a diagnostic tool but helps identify abnormal or suspicious lesions before symptoms appear, aiming to reduce cancer-related mortality. Various techniques are available to screen individuals without symptoms and catch changes early Figure 5.

Visual Examination Visual inspection is one of the most widely used and straightforward methods for oral cancer screening. It involves a thorough examination of the oral cavity by a dental or healthcare professional under adequate lighting conditions. The clinician carefully observes all areas of the mouth, including the lips, tongue, cheeks, floor of the mouth, hard and soft palate, and oropharynx, for any signs of abnormality.

This method focuses on identifying visible changes such as red or white patches (erythroplakia or leukoplakia), non-healing ulcers, unusual growths, lumps, or tissue thickening. Any change in color, texture, or symmetry may raise suspicion of a potentially malignant disorder or early-stage oral cancer ²⁶.

Despite its simplicity, visual examination is highly effective. It boasts a sensitivity of around 85%, meaning it can correctly identify a high proportion of actual cases, and a specificity of 97%, indicating a low rate of false positives. These figures suggest that when performed systematically and regularly, visual inspection is a reliable and valuable tool in early detection ²⁷.

Toluidine Blue Staining

Toluidine Blue staining offers several advantages in screening oral lesions, particularly in high-risk populations. It is a simple, quick, non-invasive, and painless procedure that is cost-effective and provides rapid results. The technique demonstrates high sensitivity, making it useful for detecting early-stage lesions, identifying epithelial dysplasia and early invasive carcinomas, delineating neoplastic margins, and evaluating tumour recurrence post-treatment. However, it also has notable disadvantages. Its low specificity makes it unreliable in distinguishing between malignant, benign or inflammatory lesions. The dye may yield false positives in cases of trauma, inflammation, or pre-neoplastic conditions, and false negatives where some malignant lesions may not retain the dye. Additionally, a positive result does not definitively confirm malignancy, and its limited diagnostic accuracy necessitates confirmation through biopsy and histopathology. The use of Toluidine Blue may also lead to overdiagnosis and unnecessary interventions Figure 3, Figure 4 ^{28, 29}.

Oral Cytology

Oral cytology involves collecting cells from the oral mucosa using a brush, tongue blade, or rinse, followed by microscopic examination after staining. Initially adapted from the cervical Pap smear, it is a simple, painless, and non-invasive technique. Despite its early introduction in 1963, its effectiveness in detecting oral cancer has been limited due to low sensitivity, often resulting from inadequate sampling and interpretive variability ^{30, 31}.

Advancements like brush cytology have improved its utility, especially in patients unable to undergo scalpel biopsy. The OralCDx® Brush Test, combining cell sampling with AI-assisted analysis, serves as a useful adjunctive tool for early detection of oral potentially malignant disorders (OPMDs). However, its diagnostic accuracy remains debated, with studies reporting mixed results regarding its sensitivity and specificity when compared to surgical biopsy ^{31, 32}.

Autofluorescence Imaging

Autofluorescence imaging is a non-invasive adjunctive technique that enhances the detection of oral lesions by highlighting changes in tissue fluorescence under specific light wavelengths. Normal mucosa emits a light-green fluorescence due to natural fluorophores like collagen and NADH, while dysplastic or cancerous tissue typically appears darker due to altered fluorescence ³³.

This technique is highly sensitive (~91%) and helps identify lesions that may need biopsy. However, it has limited specificity (~58%) as benign conditions, such as inflammation, can produce similar fluorescence loss. Therefore, it should not replace visual and tactile exams but rather complement them for more accurate diagnosis and management ³⁴.

Chemiluminescence-Based Screening

Chemiluminescence involves the emission of light resulting from a chemical reaction and is used in this context to enhance the visualization of abnormalities in the oral mucosa. The ViziLite® system, a chemiluminescent device approved by the FDA, uses light at specific wavelengths (430-580 nm) after a rinse with 1% acetic acid to highlight suspicious lesions ³⁴.

Abnormal tissue appears white (acetowhite), while normal mucosa displays a bluish tone. Although it is effective in detecting lesions such as leukoplakia, which may go unnoticed during conventional visual examinations, its low specificity limits its diagnostic accuracy, as it cannot reliably distinguish between benign, inflammatory, or potentially malignant conditions, potentially leading to unnecessary biopsies ³⁵.

HPV Screening

HPV is the most prevalent sexually transmitted infection and a recognized etiological factor in oropharyngeal cancer and oral squamous cell carcinoma (OSCC). In individuals with clinically normal oral mucosa, a practical detection method consists of collecting cytological samples via a mouth rinse using sterile saline or cetylpyridinium chloride. These samples are then analyzed using molecular techniques such as SPF10-LiPA to detect and genotype oncogenic HPV strains ³⁶.

Screening programs have shown that identifying and monitoring individuals with persistent high-risk HPV infections can enable early intervention. In a longitudinal study of 665 cancer-free participants, mouth rinse and saliva samples were used to detect HPV DNA. Those with positive results were monitored every 3 to 6 months, allowing early detection of oropharyngeal carcinoma in one case following prolonged viral persistence ³⁷.

Although rinse-based detection shows moderate sensitivity (~72%) and high specificity (~92%) for HPV-related head and neck cancers, sensitivity improves when combined with other biomarkers. For example, serum antibodies targeting HPV E6 proteins have demonstrated higher sensitivity for identifying individuals at risk ^{38, 39}.

Salivaomics: Salivary Biomarkers in Oral Cancer

Salivaomics refers to the comprehensive analysis of saliva using “omics” technologies including transcriptomics, genomics, proteomics, metabolomics, and microbiomics. Whole saliva, secreted by major and minor salivary glands, contains a rich mixture of molecules reflecting both systemic and local health conditions. Given its ease of collection and direct contact with oral lesions, saliva represents a promising and non-invasive medium for early oral cancer detection. Saliva contains molecular signatures associated with cancer, allowing the detection of genetic mutations, alterations in protein expression, and metabolic changes related to malignancy. Screening high-risk groups, such as tobacco users, for salivary biomarkers may enable early diagnosis and timely intervention ⁴⁰.

Recent advances have introduced saliva-based biosensors that are affordable, sensitive, and painless. Biomarkers such as CYFRA-21-1 and novel nanomaterials like lanthanum hydroxide structures coated with L-cysteine have shown promising diagnostic potential. Beyond oral cancer, these biosensors may also be applied to detect systemic diseases, including kidney and periodontal conditions ^{41, 42}. Despite challenges such as sample variability and contamination risks, the advantages of saliva-based diagnostics are significant. Continued research is essential to standardize protocols and develop reliable biosensors, paving the way for broader clinical application and improved outcomes, particularly in vulnerable populations ⁴⁰.

Digital Strategies for Oral Cancer Screening

Mobile health technologies have emerged as valuable tools to enhance oral cancer detection, especially in remote and underserved regions. Mobile applications designed for primary healthcare workers (PHCWs) have been successfully tested in countries such as India, Argentina, and Malaysia. These tools enable PHCWs to capture and transmit oral images, both normal and potentially suspicious, to remote specialists for evaluation. For instance, in India, over 3,400 industrial workers were screened using one of these applications, facilitating remote assessment and triage ^{43, 44}.

Telehealth and teledentistry further expand access to diagnostic expertise by using information and communication technologies (ICTs) that transmit clinical data remotely. Teleconsultations (TCs), which can be conducted in real time or asynchronously via messages and emails, support healthcare professionals in resolving clinical doubts and improving decision-making. Recent studies highlight the potential of these digital platforms in the early detection of potentially malignant oral lesions. As digital infrastructure continues to evolve, these tools offer scalable and cost-effective solutions to improve early diagnosis and reduce the burden of oral cancer in resource-limited settings ^{45, 46, 47}.

AI-Based Oral Cancer Detection

Artificial Intelligence (AI) is transforming the landscape of oral cancer diagnostics by improving speed and accuracy in early detection. Deep learning (DL) models trained on clinical images can distinguish between benign and malignant lesions in real time, facilitating more timely clinical decision-making. Tools such as computer-aided diagnosis (CAD) systems and AI-enhanced optical coherence tomography (OCT) offer non-invasive and efficient detection options ⁴⁸.

AI is also applied to the analysis of genetic and molecular data, helping to identify new biomarkers and personalize treatment strategies. A significant breakthrough in detection was achieved by Sankaranarayanan et al., who conducted a landmark randomized clinical trial. This study demonstrated that visual examinations by community health workers, combined with risk factor assessment, significantly reduced mortality from oropharyngeal squamous cell carcinoma in high-risk groups and proved to be a cost-effective strategy. While the potential of AI is promising, challenges remain, such as data quality, model validation, and integration into clinical workflows. When combined with traditional methods and expert clinical judgment, AI can significantly enhance early detection and outcomes, particularly in regions with limited resources and high disease prevalence ^{49, 50}.

5. Role of Health Professionals and Public Awareness

Role of Dentists in Oral Cancer Screening

Dentists play a vital role in the early detection and prevention of oral cancer through routine screening and patient education. Although high-risk individuals, such as smokers and heavy drinkers, may not visit dental clinics regularly, the dental team can provide targeted, chairside advice to those who do, raising awareness of risk factors and early signs. Since many patients with symptoms may first consult general practitioners, collaboration between dental and medical teams is essential for timely referrals. Community link-workers can also help guide high-risk patients toward dental care ⁵¹.

Dental professionals should regularly train in lesion detection and referral protocols to enhance effectiveness. Evidence-based guidelines and online modules support continued education, ensuring the dental team remains equipped to contribute meaningfully to oral cancer prevention

1. Gaps in awareness and training

A study conducted during the 101st FDI World Dental Congress in Istanbul evaluated oral cancer awareness among 170 dentists from various specialties. While most participants recognized major risk factors like tobacco (98.8%) and alcohol use (91.2%), fewer identified age (56.5%) and poor diet (52.4%) as contributors. Oral medicine specialists performed slightly better in recognizing early lesions and the common presentation of oral cancer (p < 0.01). The findings point to variability in knowledge across dental disciplines, underscoring the need for enhanced and standardized training in oral cancer detection and prevention ⁵².

In Germany, oral cavity examination is an integral part of the routine semi-annual or annual dental check-ups mandated by the healthcare system. Patients often turn to their dentists first when concerned about potential oral tumors, making dentists key figures in early detection ⁵¹.

However, while dental status is formally documented, there is no standardized requirement or form for recording oral mucosa findings. This lack of structured documentation contributes to a scarc6. ity of efficacy studies evaluating the role of dentists in oral cancer detection within private practice, a gap not unique to Germany. Standardizing documentation could enhance data collection and support evidence-based evaluation of dentists' contributions to early cancer detection ^{51, 53}.

Additionally, a cross-sectional study conducted across three dental institutions in Nepal evaluated oral cancer awareness among 508 dental students and practitioners. While a majority recognized smoking (89.96%) and tobacco chewing (77.75%) as key risk factors, only 23.6% were familiar with the clinical presentation of oral cancer, and just 39.4% identified non-healing ulcers as a warning sign. Notably, 67.7% reported lacking knowledge on prevention and detection. These findings underline significant gaps in oral cancer training, emphasizing the need to strengthen undergraduate curricula ⁵⁴.

2. Awareness among general population

Andrade et al. conducted a cross-sectional study to evaluate awareness and knowledge about oral cancer among the general population in southern Portugal. The study involved 2,650 individuals who participated in oncological screening programs. Data were collected using a structured questionnaire focusing on sociodemographic characteristics, lifestyle habits, and knowledge of oral cancer. The results showed that 83.4% of participants had heard of oral cancer. Awareness was significantly linked to age, educational level, frequency of dental visits, smoking, and alcohol consumption. While most respondents identified smoking (86%) and alcohol (58.5%) as risk factors, recognition of early signs, such as persistent ulcers (62.8%), red or white lesions (45.5%), and abnormal tissue growth (37.9%), was relatively low. The study highlighted a concerning gap in oral cancer awareness, particularly among individuals at higher risk. The authors emphasized the urgent need for targeted educational interventions aimed at improving early detection and promoting preventive behaviors in the general population ⁵⁵.

A survey conducted in Singapore assessed oral cancer awareness among various groups, including the general public. While dental and medical students showed high awareness, the general population exhibited limited knowledge beyond smoking as a risk factor. Only 41% were aware of viral causes of oral cancer, and overall awareness was notably lower in older adults compared to those aged 18-34. These findings highlight a pressing need for targeted public education to improve early detection and prevention efforts ⁵⁶.

Raising Awareness

Although approximately 86% of British adults are aware of oral cancer, understanding of its early signs, symptoms, and risk factors remains insufficient, particularly among individuals from lower educational and socio-economic backgrounds. Despite general awareness of the disease, many people fail to associate their symptoms with oral cancer, often choosing to self-manage rather than seek professional help. This contributes to delayed diagnoses and worsened outcomes. Dental professionals are in a key position to identify potential risks and offer necessary guidance to patients. Their role extends beyond clinical intervention, involving active promotion of oral cancer awareness and encouraging regular dental check-ups to facilitate early detection. Dental students and practitioners alike can contribute by engaging with patients about the risks, distributing educational materials, participating in public health campaigns such as Mouth Cancer Action Month, and utilizing digital platforms to emphasize the importance of routine screenings ⁵⁷.

3. Future Perspective in Oral Cancer Screening

The future of oral cancer screening lies in a multifaceted approach that prioritizes innovation, interdisciplinary collaboration, and accessibility. Advancements in research are expected to revolutionize early detection by identifying novel biomarkers, risk factors, and therapeutic targets. This evolving knowledge base will facilitate the development of personalized screening protocols, improving prognostic outcomes and reducing the burden of late-stage diagnoses.

The integration of cutting-edge technologies such as AI, molecular diagnostics, and non-invasive imaging holds tremendous potential. AI-powered tools can analyse large datasets with precision, aiding in the early identification of subtle mucosal changes that might be overlooked during routine examinations. Salivary diagnostics and liquid biopsies are emerging as promising non-invasive alternatives, capable of detecting molecular alterations associated with malignant transformation. Additionally, portable optical imaging systems and fluorescence-based detection devices are being refined to provide real-time, chairside screening solutions, especially beneficial in resource-limited settings ⁵⁷.

Moreover, fostering collaboration among clinicians, biomedical researchers, engineers, and public health experts is crucial to ensure that scientific breakthroughs are translated into clinically viable and widely accessible screening tools. Public health initiatives must also be strengthened to promote awareness, improve screening uptake, and reduce disparities in access to care. Tele-screening and mobile health units equipped with digital diagnostics could further extend the reach of early detection services, particularly in underserved populations. Overall, the future of oral cancer screening hinges on the successful integration of emerging technologies with patient-centred care models, paving the way for earlier diagnoses, better outcomes, and reduced healthcare costs ⁵⁸.

6. Conclusion

Oral cancer screening is a critical component in reducing the global burden of oral and oropharyngeal cancers. Advances in molecular diagnostics, such as HPV screening and salivaomics, combined with emerging technologies like AI and digital health platforms, have significantly enhanced early detection capabilities. These innovations promise to improve sensitivity and specificity, particularly when integrated with traditional clinical examination and risk assessment.

Despite technological progress, significant gaps remain in awareness and training among both health professionals and the general population. Dentists and primary healthcare workers are pivotal in screening and patient education, yet standardized training and documentation practices need strengthening to maximize their impact. Furthermore, public knowledge about risk factors and early signs remains insufficient, especially in high-risk and underserved groups, underscoring the urgent need for targeted educational campaigns.

Looking forward, a multifaceted, patient-centered approach combining cutting-edge diagnostics, interdisciplinary collaboration, and widespread public health initiatives is essential. The integration of non-invasive, affordable, and accessible screening methods, bolstered by telehealth and mobile technologies, will be crucial in reaching vulnerable populations and ensuring equitable care. Continued research and innovation will facilitate personalized screening strategies, ultimately leading to earlier diagnosis, improved survival outcomes, and reduced healthcare costs. Emphasizing prevention, education, and technology-driven early detection is the pathway to mitigating the oral cancer burden worldwide.

References