Jaw cancer refers to malignant growths affecting the bones of the jaw (mandible or maxilla) or surrounding oral cavity tissues. While any oral cancer can involve the jaw, true jaw cancer originating within the bone is uncommon. This article details its prevalence, forms, risk factors, and global variations.
Overall Incidence and Prevalence
Jaw cancer is rare compared to many other cancers, accounting for a small percentage of head and neck cancers (about 4% of all U.S. cancers). Often, cancer found in the jaw has spread from other oral cavity parts like the tongue or palate, rather than originating in the jawbone. Globally, oral and oropharyngeal cancers are a significant public health issue, with approximately 389,846 new cases reported worldwide in 2022. Oral cancer ranks as the 16th most common cancer globally. However, cancers specifically starting in the jaw are uncommon; for instance, squamous cell carcinomas (SCCs), the most frequent type of oral cancer, rarely begin in the jawbone itself.
Types of Jaw Cancer and Their Frequencies
Jaw cancer encompasses various malignancies with differing frequencies. Squamous cell carcinoma (SCC) is the most common oral cavity cancer, accounting for over 90% of diagnoses. While SCC can involve the jaw by spreading from adjacent tissues, only a small percentage directly originate in the jawbone.
Primary bone cancers of the jaw are much less frequent. Osteosarcoma, a bone tissue cancer, can occur in the jaw, though it’s more common in long bones. Jaw osteosarcomas represent 6% to 9% of all osteosarcoma cases, with an estimated annual incidence of 0.7 per million.
Ameloblastoma, a tumor from tooth enamel tissue, is generally benign, with malignant forms being rare (1.79 per 10 million persons per year). Other exceptionally rare types include primary intraosseous carcinoma, clear cell odontogenic carcinoma, ghost cell odontogenic carcinoma, and sclerosing odontogenic carcinoma, often from tooth-forming tissues.
Key Risk Factors and Affected Demographics
Several factors increase the likelihood of developing oral cancers that can affect the jaw. Tobacco use (smoking or chewing) and excessive alcohol consumption are leading risk factors; combining them further elevates risk. Betel nut chewing, common in parts of Asia, also contributes.
Human papillomavirus (HPV) infection is another risk factor, particularly for certain oral cancers, increasing risk in younger individuals. Poor nutrition (low in fruits and vegetables) and poor oral hygiene are also linked to increased risk. Genetic predispositions can play a role.
Oral cancers are more common in older adults, with an average diagnosis age of 64 years, though about 20% occur in those younger than 55. Historically, these cancers are more prevalent in men, with incidence rates nearly three times higher for males than females.
Global Trends and Regional Differences
Global oral cancer incidence, including those affecting the jaw, shows varying trends. From 1990 to 2021, the global incidence rate increased, though trends differ by specific sites and regions. For instance, lip cancer rates have decreased for both sexes in many populations.
Mouth cancer shows a more complex pattern, with decreasing rates in males but increasing rates in females in some populations. South and Southeast Asia report some of the highest global oral cancer incidence, with countries like India, Pakistan, and Bangladesh having substantial cases.
These regional variations link to prevalent risk factors like tobacco and betel nut use. Changes in tobacco and alcohol consumption patterns also influence global trends.