PREV 701 Cancer Epidemiology
October 29, 2012
Epidemiology of Esophageal Cancer
Esophageal cancer is a gastrointestinal malignancy with an insidious onset and a poor prognosis. Although some patients can be cured, the treatment for esophageal cancer is protracted, decreases quality of life, and is lethal in a significant number of cases. The etiology of esophageal carcinoma is thought to be related to exposure of the esophageal mucosa to noxious or toxic stimuli, resulting in a sequence of dysplasia to carcinoma in situ to carcinoma. By far, the most common esophageal cancer worldwide is squamous cell carcinoma, while the second common subgroup—adenocarcinoma accounts for less than 15% of all esophageal cancers1. Other malignant tumors of the esophagus, such as sarcomas, lymphoma, primary malignant melanoma, and small cell carcinoma, are very rare. Although the clinical treatment of those two main histopathologic types of esophageal cancer, squamous cell carcinoma and adenocarcinoma, is often the same, the etiology and epidemiology are quite different. Therefore, increasing the understanding on the epidemiology of each histopathologc types of esophageal cancer could be helpful to the preventive strategies and treatment. Descriptive epidemiology
Geographic and demographic distribution
Currently, esophageal cancer, which includes squamous cell carcinoma and adenocarcinoma, types) is the eighth most common incidence of cancer in the word: 481,000 new cases (3.8% of the total) were diagnosed in 2008; and it ranks sixth among all cancer mortality cases because of its extremely aggressive nature and poor survival rate.2 It predominantly affects older age groups: the incidence rate increases as the age grows; children and young adult cases are rarely seen. Additionally, males have almost four times higher incidence rate than females do (Figure 1). Those trends are consistent globally, but generally the rates are higher in less developed regions than those in the more developed regions (Figure 2). Worldwide, about 83% of the cases occur in economically less developed regions (Figure 3). In both sexes and in all ages, the difference is about 16-fold between the highest-risk southern Africa area and the lowest-risk middle Africa area (Figure 4). Other areas of relatively high risk are eastern Asia, eastern Africa, and Eastern Africa (Figure 5). In terms of the major subgroup of esophageal cancer—squamous cell carcinoma, it is important to mention the infamous “Asian esophageal cancer belt”3 (Figure 6), which passes from Turkey through countries such as Iraq, Iran, and Kazakhstan, and on to northern China. This region is known to have the highest incidence rates for esophageal cancer in the world. There are also some “hot spots” of squamous cell carcinoma in the more developed regions, including northwestern France, Iceland, Scotland, Finland, and in the United States in coastal South Carolina and metropolitan Washington, DC/Baltimore4. In regards to adenocarcinoma of the esophagus, it is predominantly a disease of Western Europe, Australia, and North America. Especially in the United States, the reported annual increase of 10% made esophageal adenocarcinoma the most rapidly increasing type of cancer among white U.S. men5, and it surpassing squamous cell carcinoma around 1990.6 Epidemiological characteristics of esophageal cancer in China Overall, esophageal cancer ranks second in incidence in China7. The age-specific incidence rate among the elderly (≥65 years old) is two times higher than those <65 years of age. The incident cases among those < 45 years old, account for less than 5% of the total incident cases in China (Table 1). As mentioned earlier, squamous cell carcinoma remains the dominant histopathology subtype. The prediction model estimated that there will be a big increase on the incident numbers: 484,923 new cases for both sexes in 2030. Among...