Smoking in America is down -- but not out. Today, 20% of U.S. adults are smokers, compared to 45% in 1965, when smoking was at its peak. But even at the current level of tobacco use, an estimated 440,000 Americans per year lose their lives to lung cancer, heart disease, emphysema, or other smoking-related illnesses. On average, smokers die 14 years before nonsmokers, and half of all smokers who don't quit are killed by their habit.
People start smoking for many reasons. Many continue to puff away...
Over the period from 2004 to 2008, the estimated incidence of oral cancer in the United States was 10.6 cases per 100,000 persons per year. The most recent estimated mortality rate (from 2003-2007) was 2.5 per 100,000 persons per year. U.S. incidence and mortality rates are about 2.5 and 2.8 times higher, respectively, in men than women. It is estimated that there will be 39,400 new cases of oral cancer diagnosed in the United States in 2011 and 7,900 deaths due to this disease. The estimated age-standardized (World Standard Population) worldwide incidence and mortality rates of oropharyngeal cancer in 2008 were 5.9 and 3.3 per 100,000 persons per year, respectively. Primarily due to differences in tobacco and alcohol use, there is wide variation in rates across the world. South central Asia and Melanesia have particularly high rates of oral cancer attributable to betel quid chewing, and Australia has a high rate of lip cancer attributed to solar irradiation.
Oral cancer can be divided into three clinicopathological categories: carcinoma of the lip vermillion, carcinoma of the oral cavity proper, and carcinoma of the oropharynx.
Squamous cell carcinoma, which arises from the oral mucosal lining, accounts for more than 90% of the tumors in the oral cavity and oropharynx. Other types of primary tumors arising in this area include lymphoma, sarcoma, melanoma, and minor salivary gland tumors. In the Western world the most common locations of tumor development are the tongue and floor of the mouth; however, in parts of the world where tobacco or betel quid chewing is prominent, cancers of the retromolar trigone and buccal mucosa are common. Oral squamous cell carcinomas are sometimes preceded by oral preneoplastic lesions, which are often present as visible alterations of the mucosal surface and include leukoplakia and erythroplakia.
The most important factor affecting long-term outcome after treatment is the stage of disease at diagnosis; however, overall outcome is stage and site dependent. Although early-stage tumors (without lymph node involvement) have an excellent anticipated 5-year survival rate (about 82%), the 5-year survival rates for patients with regional lymph node spread or metastases are only about 56% and 34%, respectively. Some or all of the differences in prognosis among disease stages may be due to lead-time bias rather than a benefit of early detection and treatment. (Refer to the PDQ summary on Cancer Screening Overview for more information.)
Factors associated with increased risk of oral cancer
Tobacco use is responsible for more than 90% of tumors of the oral cavity among men and 60% among women, and is responsible for 90% of oral cancer deaths in males. All forms of tobacco-cigarettes, pipes, cigars, and smokeless tobacco-have been implicated in the development of oral cancers. While tobacco confers the highest risk for cancer of the floor of the mouth, it is associated with an increased risk for all sites of oral cancer.