Chapter 087. Gastrointestinal Tract Cancer (Part 1)

Harrisons Internal Medicine Chapter 87. Gastrointestinal Tract CancerGastrointestinal Tract Cancer: IntroductionThe gastrointestinal tract is the second most common noncutaneous site for cancer and the second major cause of cancer-related mortality in the United States.Esophageal CancerIncidence and Etiology Cancer of the esophagus is a relatively uncommon but extremely lethal malignancy. The diagnosis was made in 15,560 Americans in 2007 and led to13,940 deaths. Worldwide, the incidence of esophageal cancer varies strikingly. ...
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Chapter 087. Gastrointestinal Tract Cancer (Part 1) Chapter 087. Gastrointestinal Tract Cancer (Part 1) Harrisons Internal Medicine > Chapter 87. Gastrointestinal Tract Cancer Gastrointestinal Tract Cancer: Introduction The gastrointestinal tract is the second most common noncutaneous site forcancer and the second major cause of cancer-related mortality in the United States. Esophageal Cancer Incidence and Etiology Cancer of the esophagus is a relatively uncommon but extremely lethalmalignancy. The diagnosis was made in 15,560 Americans in 2007 and led to13,940 deaths. Worldwide, the incidence of esophageal cancer varies strikingly. Itoccurs frequently within a geographic region extending from the southern shore ofthe Caspian Sea on the west to northern China on the east and encompassing partsof Iran, Central Asia, Afghanistan, Siberia, and Mongolia. High-incidencepockets of the disease are also present in such disparate locations as Finland,Iceland, Curaçao, southeastern Africa, and northwestern France. In North Americaand western Europe, the disease is more common in blacks than whites and inmales than females; it appears most often after age 50 and seems to be associatedwith a lower socioeconomic status. A variety of causative factors have been implicated in the development ofthe disease (Table 87-1). In the United States, esophageal cancer cases are eithersquamous cell carcinomas or adenocarcinomas. The etiology of squamous cellesophageal cancer is related to excess alcohol consumption and/or cigarettesmoking. The relative risk increases with the amount of tobacco smoked oralcohol consumed, with these factors acting synergistically. The consumption ofwhiskey is linked to a higher incidence than the consumption of wine or beer.Squamous cell esophageal carcinoma has also been associated with the ingestionof nitrites, smoked opiates, and fungal toxins in pickled vegetables, as well asmucosal damage caused by such physical insults as long-term exposure toextremely hot tea, the ingestion of lye, radiation-induced strictures, and chronicachalasia. The presence of an esophageal web in association with glossitis and irondeficiency (i.e., Plummer-Vinson or Paterson-Kelly syndrome) and congenitalhyperkeratosis and pitting of the palms and soles (i.e., tylosis palmaris et plantaris)have each been linked with squamous cell esophageal cancer, as have dietarydeficiencies of molybdenum, zinc, and vitamin A. Table 87-1 Some Etiologic Factors Believed to Be Associated withEsophageal Cancer Excess alcohol consumption Cigarette smoking Other ingested carcinogens Nitrates (converted to nitrites) Smoked opiates Fungal toxins in pickled vegetables Mucosal damage from physical agents Hot tea Lye ingestion Radiation-induced strictures Chronic achalasia Host susceptibility Esophageal web with glossitis and iron deficiency (i.e., Plummer-Vinsonor Paterson-Kelly syndrome) Congenital hyperkeratosis and pitting of the palms and soles (i.e., tylosispalmaris et plantaris) ? Dietary deficiencies molybdenum, zinc, vitamin A ? Celiac sprue Chronic gastric reflux (i.e., Barretts esophagus) for adenocarcinoma For unclear reasons, the incidence of squamous cell esophageal cancer hasdecreased somewhat in both the black and white population in the United Statesover the past 30 years, while the rate of adenocarcinoma has risen dramatically,particularly in white males. Adenocarcinomas arise in the distal esophagus in thepresence of chronic gastric reflux and gastric metaplasia of the epithelium(Barretts esophagus), which is more common in obese persons. Adenocarcinomasarise within dysplastic columnar epithelium in the distal esophagus. Even beforefrank neoplasia is detectable, aneuploidy and p53 mutations are found in thedysplastic epithelium. These adenocarcinomas behave clinically like gastricadenocarcinoma and now account for >60% of esophageal cancers.