Introduction
Oral cancers are complex diseases from various underlying causes, known as etiologies. These cancers may develop due to lifestyle factors such as tobacco and alcohol use, viral infections, genetic predisposition, or other medical conditions. Understanding the diverse causes of oral cancers is essential for early detection, effective treatment, and improving patient outcomes. By exploring these etiologies, we gain insights into the risk factors and preventative measures that can help reduce the global burden of oral cancers.
How Do Oral Cancers Arise Because of Different Etiologies?
Oral cancers are known to have a higher prevalence in men, with global incidence rates pinpointing Southern Asian regions, where tobacco and alcohol use are considered the primary detrimental risk factors for these head and neck cancers. Even in developed countries like the United States, high-risk cancers of the head and neck are more prevalent among individuals who are dependent on both alcohol and tobacco—two major detrimental risk factors that can induce cancers over a prolonged period, as per current oral oncologic research. According to 2018 cancer research studies highlighting global cancer statistics, lip and oral cavity cancers continue to be one of the primary areas of tumor involvement in the orofacial or head and neck regions. These cancers are followed by those affecting the nasopharynx, oropharynx, hypopharynx, or salivary glands.
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Sarcomas and Carcinomas: The maxilla and mandible—the upper and lower jaws, respectively—harbor the oral cavity and are among the most common sites affected by malignant cancers or neoplasms, such as sarcomas or carcinomas, according to the latest oncologic medical research studies. While sarcomas typically originate from the mesenchymal parts of the upper or lower jaw, carcinomas tend to originate within the primary regional lesions of the oral cavity or the oral mucosa.
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Secondary Metastasis: Carcinomas can manifest as an extension of the spread or metastasis of a primary tumor from other organs or regions, such as adenocarcinomas of the breast, prostate, thyroid, uterus, or colon. Metastases contribute to almost eight percent of oral malignancies documented in oral oncology literature. However, due to the bone marrow scarcity in the maxilla and mandible regions, less than one percent of oral malignancies are severe, high-grade bone metastases affecting individuals of any age group.
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Osteomyelitis: Chronic osteomyelitis presents a complex challenge and is a classic example in the differential diagnosis of primary cancers affecting the oral and maxillofacial regions. There are various types of jaw osteomyelitis, including purulent forms, osteoradionecrosis-based osteomyelitis, and noninfectious or diffuse sclerosing osteomyelitis. Untreated lesions of osteomyelitis progressing to oral cancers significantly increase the global incidence rates of oral cancers.
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Medication-Related Osteonecrosis (Mronj): This condition is a common medication-induced jaw disease that causes different subtypes of osteomyelitis globally. MRONJ is not only a diagnostic challenge for oral and maxillofacial surgeons. Still, it is also associated with the use of anti-bone resorption drugs such as Denosumab, antiangiogenic medications like Sorafenib, or Bisphosphonate therapies. According to research, the incidence of MRONJ is approximately 12 percent. Globally, this condition is rising due to an increase in patients undergoing bisphosphonate therapies, particularly in the United States. Untreated or unresolved lesions may progress to cancer. Castration-resistant prostate carcinomas, common in individuals on bisphosphonate therapies, can metastasize to oral cancers.
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Squamous Cell Carcinoma: Squamous cell carcinoma is the most common type of cancer, affecting nearly 90 percent of the head and neck regions, with a higher incidence in the larynx and oral cavity. Other cancer types that can metastasize to the oral cavity or head and neck regions include salivary gland adenocarcinomas, melanomas, lymphomas, and paragangliomas.
Which Carcinogenic Subtypes Are Associated With Human Papillomavirus and Epstein-Barr Virus?
HPV lesions and Epstein-Barr virus infections are linked to head and neck cancers involving regions such as the oropharynx, tonsils, tongue base, nasopharynx, larynx, and salivary glands. Researchers attribute the rise in these cancers to the combined impact of these viral lesions in orofacial and head and neck regions.
Due to their varied clinical manifestations, viral-driven cancers often present diagnostic challenges, making early detection crucial. Improved public awareness and advancements in diagnostic techniques are vital to tackling the growing prevalence of these malignancies. Additionally, lifestyle modifications and vaccination programs targeting HPV have shown promise in reducing the incidence of related cancers. Enhanced understanding and early interventions can significantly improve patient outcomes.
In maxillofacial surgery, detecting varied cancers is pivotal in determining the overall prognosis. Globally, certain types of oral cancers are on the rise due to poor oral hygiene, lack of dental awareness, missed follow-ups, untreated oral infections, severe disease progression, or viral and multi-organ-induced secondary tumors.
How Effective Is Radionuclide Imaging for Detecting High-Grade Cancers?
Bone scintigraphy research has proven to be one of the most effective diagnostic tools for MRONJ in the early stages. With a sensitivity of approximately 67 percent and a specificity of 79 percent, this advanced radiographic methodology is considered a potent technique for detecting the early asymptomatic stages of cancer in patients affected by MRONJ.
While radionuclide imaging studies such as bone scintigraphy, PET/CT (positron emission tomography/computed tomography) scans, and lymphoscintigraphy are highly beneficial in detecting the early stages of cancers in the head and neck, current oral oncologic research indicates that only one-third of cancer patients presenting with early-stage features have a better prognosis. In contrast, the remaining two-thirds of affected head and neck or oral cancer patients often present to the maxillofacial surgeon or dentist in the advanced stages.
Conclusion
Several etiologies can underlie the development of low-grade or high-grade cancers in the oral region. These conditions range from jaw-based osteomyelitis, jaw orofacial trauma, and osteoarthritis, which are positive in bone scans. Early diagnosis can be life-saving in most oral or head and neck cancers. While resection of oral tumors through surgery, usually followed by radiotherapy, is beneficial to the overall prognosis in the initial or early stages of most oral cancers, secondary or high-grade cancers can often recur as a result of metastasis from other organs.
