What is oral cancer?

Oral cancer invades the entire oral cavity including the lips, tongue, under the tongue, mouth and throat.¹ Oral cancer is grouped under head and neck cancers, which are all often treated similarly. It is the sixth most common cancer worldwide, with increasing incidence rates since 2018, being higher in men than in women globally. In general, people assigned male at birth (AMAB) face a lifetime risk of approximately 1 in 59 for developing oral cavity and oropharyngeal cancer, while people assigned female at birth (AFAB) risk stands at around 1 in 139. Along with tobacco users, it is increasingly common in young adults and is diagnosed mostly in developing nations such as Southern Asia and Brazil. 

Moreover, when we compare the number of oral and oropharyngeal cancers in young people to the total cases, we see a big difference between North America (5.5%) and Africa (17.2%) as well as the Middle East (14.5%). The trends in oral cancer incidence among young adults are concerning, showing an increase in recent years.¹

Risk factors for oral cancer

The causes of cancer are not quite clear, but there are evident factors that lead to mouth cancer such as alcohol consumption, smoking tobacco (cigarettes, pipes, cigars), or a low mineral and vitamin diet, which all weaken the immune system. This weakened immune system allows the invasion of the body by harmful pathogens such as viruses. The Human papillomavirus (HPV) spreads through the skin during sexual intercourse and infects the skin and the cells lining the body cavities. In particular, HPV 16 is found most commonly in cases of oral cancer, since it can cause changes in the lining tissue of the mouth and throat.² 

Excessive exposure to sunlight can also affect the lips, which are susceptible to the harmful effects of ultraviolet (UV) radiation. The lower lip, in particular, is often exposed to sunlight, making it vulnerable to UV-induced damage which might lead to lip cancer.^1,2,3

Management of oral cancer

 Early detection of oral cancer is crucial to refer individuals for specialised treatment promptly. Unfortunately, many cases are diagnosed at an advanced stage of the disease. While radiotherapy and surgery continue to be the main cures for the disease, advancements in understanding tumour characteristics and improvements in surgical and radiotherapy methods have led to a more systematic approach to managing the condition.¹

Surgery

The use of computed tomography (CT) and magnetic resonance imaging (MRI) has enhanced the ability to visualise the size and scope of primary tumours, as well as improved the evaluation of cervical lymph nodes. These technologies therefore allow a more precise extraction of the malignant tissues. Doctors use special techniques involving cutting the jawbone or upper jawbone to make sure they remove enough of the tumour during surgery. These techniques let them move these bones away from the surgery area, so they can reach any part inside the mouth that needs treatment.^1,4

Radiation therapy

Advanced planning using special CT images of the tumour helps doctors give radiation therapy that fits the shape of the infected tissue. This method, called conformal radiation therapy, is precise and has led to the development of intensity-modulated radiation therapy (IMRT). IMRT is an improved version of conventional radiotherapy where radiation intensity varies depending on the angle of inflexion to reduce the amount of radiation reaching healthy tissues.^4,5

Chemotherapy

Chemotherapy is a treatment using drugs to fight cancer. Its main role is to destroy cancer cells. It is called a systemic treatment because it works all over your body. Doctors sometimes use the term "cytotoxic", referring to the toxic effect chemotherapy has on cells. Cytotoxic chemotherapy works by interfering with the synthesis and replication of DNA in cells, causing them to die. In cases of stage 3 or 4 cancer, radiotherapy alone is often not effective enough and a more invasive approach is required. Therefore, chemotherapy is incorporated into the treatment plan as part of the efforts to cure the cancer.^4,5

Future directions in oral cancer treatment 

Even with notable advancements in oral cancer treatment, the death rate remains elevated. Less than half of patients typically survive after being diagnosed with mouth or throat cancer. Contemporary cancer therapies strive to enhance survival without disease, prolong progression-free survival, maintain control over local and regional areas affected by the cancer, and decrease the likelihood of disease recurrence. 

Advanced optical imaging technique

Identifying oral squamous cell carcinoma (OSCC) through traditional screening techniques like brush biopsy and in vivo confocal imaging has drawbacks. Many studies indicate that brush biopsy often shows moderate sensitivity and lacks specificity. Additionally, patients with positive results or any suspicious lesions typically require scalpel biopsy for confirmation.³

Oral cancer detection using nanoparticles

Because nanoparticles (NPs) are incredibly tiny (1–100 nm), easy to modify on their surfaces, and can efficiently connect with biological molecules, such as cancerous cells. They can be manufactured to bear different properties, such as being fluorescent or bearing magnetic properties, which enhance the accuracy of different screening techniques like immunofluorescent imaging or MRI respectively. Due to this they are a very promising tool in the future of cancer screening.^3,6

Saliva as a diagnostic tool

Over the last few decades, saliva has gained prominence as a significant diagnostic fluid for oral cancer. This is due to the presence of key molecules like tumour biomarkers, mRNA, enzymes, cytokines, and DNA abnormalities. Therefore, saliva analysis can be beneficial for predicting disease outcomes and monitoring patients after treatment.³

Conclusion

In conclusion, oral cancer remains a significant health concern globally, with high mortality rates despite advancements in treatment. Management typically involves surgery, radiation, and chemotherapy. Emerging imaging techniques aid in treatment planning, while saliva-based diagnostics show promise for early detection. Continued research and awareness efforts are essential for improving outcomes and reducing the burden of this disease.