Squamous cell carcinoma of the esophagus does not have a highly prevalent predisposing condition, although the incidence increases in persons who have had long-standing exposure to tobacco and alcohol, achalasia, head and neck squamous cell cancer attributable most likely to long-standing alcohol and/or tobacco exposure, tylosis,[4,5] history of lye ingestion, celiac sprue, and, in South America and China, hot liquid ingestion. The etiological role of human papillomavirus infection in squamous cell cancer is under study.[9,10]
Almost all hypopharyngeal cancers are epithelial in origin, predominantly squamous cell (i.e., epidermoid) carcinomas (SCCs), and may be preceded by various precancerous lesions.[1,2] Rare types of hypopharyngeal carcinomas include the following:
Basaloid squamoid carcinomas.
Spindle-cell (i.e., sarcomatoid) carcinomas.
Nasopharyngeal-type undifferentiated carcinomas (i.e., lymphoepitheliomas).
Carcinomas of the minor salivary glands.
Efforts at early detection of squamous cell cancer of the esophagus have concentrated on cytological or endoscopic screening of populations in countries where there is a high incidence. Although these programs have demonstrated that it is possible to detect squamous cell cancers in an early asymptomatic stage, no data on efficacy (e.g., mortality reduction) have been published. Esophageal cytological screening studies have been reported from China,[11,12] Iran, South Africa,[14,15] Italy, and Japan. In the United States, such efforts have been focused on individuals perceived to be at higher risk.[18,19] Studies of primary endoscopic screening have been reported from France  and Japan.
Comparisons of both Chinese and U.S. cytological diagnoses with concurrent histological findings showed low (14% to 36%) sensitivities for the cytological detection of biopsy-proven cancers. Specificity ranged from 90% to 99% with a positive predictive value of 23% to 94%. The development of uniform and accurate cytological criteria will require formal cytological-histological correlation studies of esophageal lesions. Such studies should become more feasible with the increasing availability of endoscopy in high-risk populations.
The efficacy of surveillance cytology or endoscopy for high-risk patients with tylosis or long-standing achalasia is not known.
Adenocarcinoma of the Esophagus
Considerable debate has ensued concerning the risk of cancer in patients with Barrett esophagus. Prospective studies have reported annual esophageal cancer incidence rates ranging from 0.2% to 1.9%. Concern over publication bias has led some authors to suggest that the risk may be lower than the literature suggests. A risk of 0.5% per year for development of adenocarcinoma is now thought to be a reasonable estimate for Barrett esophagus.
Barrett esophagus is strongly associated with gastroesophageal reflux disease (GERD), and the changes of Barrett esophagus can be found in approximately 10% of patients who have GERD. However, GERD is very common; surveys have found that approximately 20% of adult Americans experience symptoms of GERD, such as heartburn, at least once each week. The likelihood of finding Barrett esophagus on endoscopy is related to the duration of symptoms of gastroesophageal reflux. In a series of 701 individuals, 4% of those with symptoms for less than 1 year had Barrett esophagus on endoscopy, whereas Barrett esophagus was found in 21% of those with more than 10 years of symptoms of GERD. It has been estimated that physicians identify only approximately 5% of the population who have Barrett esophagus. There is insufficient evidence that population screening for Barrett esophagus reduces cancer mortality.[28,29]