The upper gastrointestinal (UGI) system, as addressed within this chapter, is comprised of the esophagus, the stomach, and the small intestine. Anatomically, the cervical esophagus is bordered superiorly by the hypopharynx and inferiorly by the thoracic inlet. The intrathoracic esophagus extends to the diaphragmatic hiatus, from where the intra-abdominal esophagus extends to the esophagogastric junction (EGJ). The gastric cardia, identified by origin of the rugal folds, represents the highest part of the stomach, followed by fundus, body, antrum, and pylorus. Duodenum, jejunum, and ileum are the three major small bowel components. Malignant tumors even within the same part of the UGI tract may require distinct therapeutic interventions based on their location (i.e., cervical vs. lower thoracic esophagus, duodenum vs. ileum). EGJ cancer, while possibly a special entity when it comes to therapeutic decision making, lacks separate epidemiologic data and is therefore embedded, based on EGJ cancer type and the United States Surveillance, Epidemiology and End Results (SEER) distinction, within esophageal or gastric cancer data. In the 7th edition of the American Joint Committee on Cancer (AJCC) staging from 2010, EGJ cancer stage criteria follow those of esophageal adenocarcinoma.1
Worldwide Incidence and Mortality
According to the latest data from the International Agency for Research on Cancer, esophageal cancer is currently the eighth most common cancer worldwide and the sixth most deadly.2 Age-adjusted incidence rates (AAIR, which we will report per 100,000 population) in less developed regions were over twice those of more developed regions (8.6 vs. 3.6).2 Geographical areas with the highest AAIR were Southern Africa and Eastern Asia (16.3 and 14.2), whereas the lowest AAIR occurred in Middle and Western Africa (1.1 and 1.2, respectively). As esophageal cancer is most often diagnosed at a more advanced disease stage, the incidence-mortality ratio is high, with age-adjusted mortality rates (AAMR) of 7.3 and 2.9 in less developed regions and more developed regions, respectively.2
Patient Demographic Characteristics
Esophageal cancer is a disease that occurs more often in men than in women, with worldwide AAIR of 10.1 in men compared to 4.2 in women.2 This difference is greater in more developed regions, where the incidence ratio between males and females is 5.4:1 compared to 2.1:1 in less developed regions.2 Data from the SEER program show that from 2006 to 2010, AAIR were 7.7 in men compared to 1.8 in women.3 Reasons for this sex disparity are likely related to abdominal obesity, a condition more prevalent in males than females, as well as lifestyle differences such as smoking and alcohol consumption.4,5
In the United States, the median age of esophageal cancer diagnosis is 67, with rates highest in those aged 65 to 74; less than 15% of esophageal cancer patients are under 55.3 Incidence rates in black and non-Hispanic ...