## 4 Need for Early Diagnosis  
Overall, 15% to 50% of people who have oral cancer (OC) will live for at least five years. This is because most oral tumors are found at an advanced stage (stage III or stage IV) [3]. In contrast, if OC is detected and treated early, such as at stage I or stage II, the survival rate can surpass 80% [10; 18]. In general, OC can be diagnosed by several clinical procedures, such as physical and histological examinations, biopsy, spectroscopic, radiographic techniques, and so on (Table 1). The early discovery of cancer is essential for averting additional psychological, physical, and financial losses for the patient. Numerous unique procedures have been developed as a result of advances in science and technology that offer benefits over currently used traditional diagnostic methodologies.  
The molecular biology findings are useful in solving the many new issues that arise in the detection and diagnosis of OC. These methods can detect any changes at the molecular level considerably earlier than a microscope can detect them, and well before clinical changes occur. Oral lesions can also be classified based on their molecular characteristics. As a result, it is now possible to predict the toxic potential of ulcerations, meaning that the number of oral cancers will go down and that early detection and treatment will be better [19; 20; 21; 22; 23]. There has been a lot of progress in our understanding of the human genome, as well as different ways to study genetics and molecular biology. These tools can be used to quickly diagnose and treat oral lesions through molecular examination. In today's world, molecular biology helps us comprehend pathological progressions and development at a level beyond the human sight by revealing the characteristics and functional properties of macromolecules. The application of molecular diagnostic tools to determine disease risk,  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Method** & **Sample Type** & **Highlight** \\ \hline Physical examination (visual) & Oral cavity (in situ) & Low cost and decreased death and morbidity \\ Vital staining (visual) & Oral tissue & Low cost and non-invasive \\ Histopathology & Oral tissue & Large sample can be analyzed \\  & **Biopsy** & \\ Brush biopsy & Oral cells & Non-invasive, painless, and low cost \\ Liquid biopsy & Biofluids & Fast, less invasive, and complete sample profile \\ Incisional biopsy & Oral tissue & Less sample; specific and accurate \\ exfoliative biopsy & Epithelial cells & Low cost and minimum skills \\  & **Imaging Techniques** & \\ CT scan & Tissue (in situ) & Rapid, good visualization \\ MRI scan & Tissue (in situ) & Non-invasive and high-resolution image \\ Optical coherence topography & Oral tissue & Non-invasive and high-resolution image \\  & **Molecular method** & \\ PCR & Biofluids, cells & High sensitivity and reproducibility \\ Mass spectroscopy & Tissue (proteins/lipids) & Accurate and high specificity \\ \hline \hline \end{tabular}
\end{table}
Table 1: Traditional methods for detecting oral cancer.  
their presence, and therapy efficacy is referred to as molecular diagnostics. Microarrays, deep sequencing methods, and proteomics methods are often used to study the molecular level of OC and for its early diagnosis. In the past, high-throughput methods were used to find biomarkers in saliva and plasma or predictive markers in tissue specimens that were used to find biomarkers [24].