Head and Neck Tumors

In 2006, it was estimated that head and neck cancers comprised 2%–3% of all cancers in the United States and accounted for 1%–2% of all cancer deaths. This total includes 22,040 cases of oral cavity cancer, 9,510 cases of laryngeal cancer, and 8,950 cases of pharyngeal cancer. Most patients with head and neck cancer have metastatic disease at the time of diagnosis (regional nodal involvement in 43% and distant metastasis in 10%).

Head and neck cancers encompass a diverse group of uncommon tumors that frequently are aggressive in their biologic behavior. Moreover, patients with a head and neck cancer often develop a second primary tumor. These tumors occur at an annual rate of 3%–7%, and 50%–75% of such new cancers occur in the upper aerodigestive tract or lungs.

The anatomy of the head and neck is complex and is divided into sites and subsites (Figure 1). Tumors of each site have a unique epidemiology, anatomy, natural history, and therapeutic approach. This chapter will review these lesions as a group and then individually by anatomic site.

Epidemiology

Gender Head and neck cancer is more common in men; 66%–95% of cases occur in men. The incidence by gender varies with anatomic location and has been changing as the number of female smokers has increased. The male-female ratio is currently 3:1 for oral cavity and pharyngeal cancers. In patients with Plummer-Vinson syndrome, the ratio is reversed, with 80% of head and neck cancers occurring in women.

Age The incidence of head and neck cancer increases with age, especially after 50 years of age. Although most patients are between 50 and 70 years old, head and neck cancer does occur in younger patients. There are more women and fewer smokers in the younger patient group.

It is controversial whether head and neck cancer is more aggressive in younger patients or in older individuals. This "aggressiveness" probably reflects the common delay in diagnosis in the younger population, since, in most studies, younger patients do not have a worse prognosis than their older counterparts.

Race The incidence of laryngeal cancer is higher in African Americans relative to the white, Asian, and Hispanic populations.

Additionally, in African Americans, head and neck cancer is associated with lower survival for similar tumor stages. The overall 5-year survival rate is 56% in whites and 34% in African Americans.

Geography There are wide variations in the incidence of head and neck cancer among different geographic regions. The risk of laryngeal cancer, for example, is two to six times higher in Bombay, India, than in Scandinavia. The higher incidence of the disease in Asia is thought to reflect the prevalence of risk factors, such as betel nut chewing and use of smokeless tobacco. In the United States, the high incidence among urban males is thought to reflect exposure to tobacco and alcohol. Among rural women, there is an increased risk of oral cancer related to the use of smokeless tobacco (snuff).

Nasopharyngeal carcinoma is another head and neck tumor with a distinct ethnic predilection. Endemic areas include southern China, northern Africa, and regions of the far Northern Hemisphere—areas in which the diet of inhabitants includes large quantities of salted meat and fish. When people from these regions migrate to areas with a lower disease incidence, their risk falls but remains elevated. Cancer of the nasopharynx in these geographic areas also has been associated with Epstein-Barr virus (EBV) infection (see section on "Etiology and risk factors").

Etiology and risk factors

Risk factors for head and neck cancer include tobacco and alcohol use, ultraviolet (UV) light exposure, viral infection, and environmental exposures.

Tobacco The incidence of head and neck tumors correlates most closely with the use of tobacco.

Cigarettes Head and neck tumors occur six times more often among cigarette smokers than nonsmokers. The agestandardized risk of mortality from laryngeal cancer appears to rise linearly with increasing cigarette smoking. For the heaviest smokers, death from laryngeal cancer is 20 times more likely than for nonsmokers. Furthermore, active smoking by head and neck cancer patients is associated with significant increases in the annual rate of second primary tumor development (compared with former smokers or those who have never smoked). Use of unfiltered cigarettes or dark, aircured tobacco is associated with further increases in risk.

Cigars Total cigar smoking increased by nearly 50% in the United States in the 1990s. Often misperceived as posing a lower health risk than cigarette smoking, cigar smoking results in a change in the site distribution for aerodigestive tract cancer, according to epidemiologic data. Although the incidence of cancer at some sites traditionally associated with cigarette smoking (eg, larynx, lungs) is decreased in cigar smokers, the incidence of cancer is actually higher at other sites where pooling of saliva and associated carcinogens tends to occur (oropharynx, esophagus).

Smokeless tobacco Use of smokeless tobacco also is associated with an increased incidence of head and neck cancer, especially in the oral cavity. Smokeless tobacco users frequently develop premalignant lesions, such as oral leukoplakia, at the site where the tobacco quid rests against the mucosa. Over time, these lesions may progress to invasive carcinomas. The use of snuff has been associated with an increase in cancers of the gum and oral mucosa.

Alcohol Alcohol consumption, by itself, is a risk factor for the development of pharyngeal and laryngeal tumors, although it is a less potent carcinogen than tobacco. For individuals who use both tobacco and alcohol, these risk factors appear to be synergistic and result in a multiplicative increase in risk.

UV light exposure is a risk factor for the development of cancer of the lips. At least 33% of patients with lip cancer have outdoor occupations.

Occupational exposures A small group of head and neck cancers may be attributable to occupational exposures. Nasal cancer has been associated with wood dust exposure, and squamous cell cancer of the maxillary sinus, with nickel exposure. Petroleum exposure may be associated with pharyngeal cancer, but the relationship has not been proven.

Radiation exposure Exposure to radiation is clearly an important risk factor for thyroid cancer and has been associated with cancer of the salivary glands.

Viruses There is a strong link between EBV exposure and the development of nasopharyngeal cancer. The relationship between human papillomavirus and some head and neck cancers is increasingly recognized.

Diet Epidemiologic studies suggest that dietary intake of vitamin A, ßcarotene, and atocopherol may reduce the risk of developing head and neck cancer.

Marijuana Smoking marijuana is associated with the development of head and neck cancer, but the degree of risk is unknown.