Prospective, randomized, controlled trials and meta-analyses of prospective, randomized, controlled trials.
The randomized, double-blinded, controlled trial is the gold standard of study design. To achieve this ranking, the study allocation must be blinded to the investigator both before and after the randomization and the assignment to intervention group. This design provides protection from allocation bias by the investigator and from bias in the assessment of outcomes by both the...
An estimated 41,380 new cases of oral cancer will be diagnosed in the United States in 2013, and an estimated 7,890 people will die of the disease. This form of cancer accounts for about 3% of cancers in men. The overall annual incidence in the United States is about 10.8 per 100,000 men and women; the median age at diagnosis of oral cavity or pharyngeal cancer was 62 years from 2005 to 2009.
Incidence has been falling in men since 1975 and in women since 1980. However, incidence has recently been increasing for oral cancers related to human papillomavirus (HPV) infection. About 60% of oral/pharyngeal cancers are moderately advanced (regional stage) or metastatic at the time of diagnosis.
The estimated annual worldwide number of incident oral cancers is about 275,000, with an approximately 20-fold variation geographically. South and Southeast Asia (India, Sri Lanka, Pakistan, and Bangladesh), France, and Brazil have particularly high rates. In most countries, men have higher rates of oral cancer than women (due to tobacco use) and higher rates of lip cancer (due to sunlight exposure from outdoor occupations).
The primary risk factors for oral cancer in American men and women are tobacco (including smokeless tobacco) and alcohol use. Infection with HPV-16 has been associated with an excess risk of developing squamous cell carcinoma of the oropharynx.
Evidence of Benefit Associated With Screening
No population-based screening programs for oral cancers have been implemented in developed countries, although opportunistic screening or screening as part of a periodic health examination has been advocated.[5,6] There are different methods of screening for oral cancers. Oral cancer occurs in a region of the body that is generally accessible to physical examination by the patient, the dentist, and the physician; and visual examination is the most common method used to detect visible lesions. Other methods have been used to augment clinical detection of oral lesions and include toluidine blue, brush biopsy, and fluorescence staining.
An inspection of the oral cavity is often part of a physical examination in a dentist's or physician's office. It has been pointed out that high-risk individuals visit their medical doctors more frequently than they visit their dentists. Although physicians are more likely to provide risk-factor counseling (such as tobacco cessation), they are less likely than dentists to perform an oral cancer examination. Overall, only a fraction (~20%) of Americans receive an oral cancer examination. Black patients, Hispanic patients, and those who have a lower level of education are less likely to have such an examination, perhaps because they lack access to medical care. An oral examination often includes looking for leukoplakia and erythroplakia lesions, which can progress to cancer.[8,9] One study has shown that direct fluorescence visualization (using a simple hand-held device in the operating room) could identify subclinical high-risk fields with cancerous or precancerous changes extending up to 25 mm beyond the primary tumor in 19 of 20 patients undergoing oral surgery for invasive or in situ squamous cell tumors. However, this finding has not yet been tested in a screening setting. Data suggest that molecular markers may be useful in the prognosis of these premalignant oral lesions.