Harrison's Internal Medicine Chapter 87. Gastrointestinal Tract Cancer
Gastrointestinal Tract Cancer: Introduction
The gastrointestinal tract is the second most common noncutaneous site for cancer and the second major cause of cancer-related mortality in the United States.
Incidence 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 to
13,940 deaths. Worldwide, the incidence of esophageal cancer varies strikingly. ...
(BQ) Part 1 book "Carly cancer of the gastrointestinal tract endoscopy, pathology, and treatment" presents the following contents: Case presentations - Clinical data, endoscopy, and pathology; vienna consensus criteria for pathological diagnosis; early neoplasia in barrett’s esophagus.
(BQ) Part 2 book "Carly cancer of the gastrointestinal tract endoscopy, pathology, and treatment" presents the following contents: Detection of early cancer - Is endoscopic ultrasonography effective; endoscopic treatment; natural course of early cancer; surgical treatment and survival rate of early cancer.
Table 87-5 Hereditable (Autosomal Dominant) Gastrointestinal Polyposis Syndromes
tion of Polyps gic Type
Familial adenomatous polyposis
Large intestine a
fibromas, lipomas, epidermoid cysts, ampullary cancers, congenital hypertrophy retinal of
Large intestine a
Endometri and ovarian
posis syndrome int...
(BQ) Part 1 book "Gastrointestinal physiology" presents the following contents: Peptides of the gastrointestinal tract, nerves and smooth muscle, swallowing, gastric emptying, motility of the small intestine, motility of the large intestine, salivary secretion.
Endoscopy is a fast moving field, and new techniques are constantly emerging. Gastrointestinal
endoscopy has a central role in the evaluation of gastrointestinal complaints and in the diagnosis
and management of gastrointestinal diseases. It is a very safe procedure in the general population
as demonstrated by numerous studies. Several data provide a better understanding of pathogenic
mechanisms. In recent decades, gastrointestinal endoscopy has evolved and branched out from a
visual diagnostic modality to impressive interventional capabilities.
Tumors of the Stomach
Incidence and Epidemiology
For unclear reasons, the incidence and mortality rates for gastric cancer have decreased markedly during the past 75 years. The mortality rate from gastric cancer in the United States has dropped in men from 28 to 5.8 per 100,000 persons, while in women the rate has decreased from 27 to 2.8 per 100,000. Nonetheless, 21,260 new cases of stomach cancer were diagnosed in the United
States, and 11,210 Americans died of the disease in 2007.
Etiology and Risk Factors Risk factors for the development of colorectal cancer are listed in Table 874.
Table 87-4 Risk Factors for the Development of Colorectal Cancer
Diet: Animal fat
Hereditary syndromes (autosomal dominant inheritance)
Nonpolyposis syndrome (Lynch syndrome)
Inflammatory bowel disease
Streptococcus bovis bacteremia
? Tobacco use
The etiology for most cases of large-bowel cancer appears to be related to environmental factors. The disease occurs more often in upper socioeconomic populations who live in urban areas.
Double-contrast air-barium enema revealing a sessile tumor of the cecum in a patient with iron-deficiency anemia and guaiac-positive stool. The lesion at surgery was a stage II adenocarcinoma.
Since stool becomes more formed as it passes into the transverse and descending colon, tumors arising there tend to impede the passage of stool, resulting in the development of abdominal cramping, occasional obstruction, and even perforation. Radiographs of the abdomen often reveal characteristic annular, constricting lesions ("apple-core" or "napkin-ring") (Fig. 87-2).
Clinical Features About 10% of esophageal cancers occur in the upper third of the esophagus (cervical esophagus), 35% in the middle third, and 55% in the lower third. Squamous cell carcinomas and adenocarcinomas cannot be distinguished radiographically or endoscopically.
Progressive dysphagia and weight loss of short duration are the initial symptoms in the vast majority of patients. Dysphagia initially occurs with solid foods and gradually progresses to include semisolids and liquids.
Gastric (Nonlymphoid) Sarcoma Leiomyosarcomas and GISTs make up 1–3% of gastric neoplasms. They most frequently involve the anterior and posterior walls of the gastric fundus and often ulcerate and bleed. Even those lesions that appear benign on histologic examination may behave in a malignant fashion. These tumors rarely invade adjacent viscera and characteristically do not metastasize to lymph nodes, but they may spread to the liver and lungs. The treatment of choice is surgical resection. Combination chemotherapy should be reserved for patients with metastatic disease.
Hereditary Nonpolyposis Colon Cancer Hereditary nonpolyposis colon cancer (HNPCC), also known as Lynch syndrome, is another autosomal dominant trait. It is characterized by the presence of three or more relatives with histologically documented colorectal cancer, one of whom is a first-degree relative of the other two; one or more cases of colorectal cancer diagnosed before age 50 in the family; and colorectal cancer involving at least two generations. In contrast to polyposis coli, HNPCC is associated with an unusually high frequency of cancer arising in the proximal large bowel.
Screening The rationale for colorectal cancer screening programs is that earlier detection of localized, superficial cancers in asymptomatic individuals will increase the surgical cure rate. Such screening programs are important for individuals having a family history of the disease in first-degree relatives. The relative risk for developing colorectal cancer increases to 1.75 in such individuals and may be even higher if the relative was afflicted before age 60.
Most recurrences after a surgical resection of a large-bowel cancer occur within the first 4 years, making 5-year survival a fairly reliable indicator of cure. The likelihood for 5-year survival in patients with colorectal cancer is stagerelated (Fig. 87-3). That likelihood has improved during the past several decades when similar surgical stages have been compared. The most plausible explanation for this improvement is more thorough intraoperative and pathologic staging.
Radiation therapy to the pelvis is recommended for patients with rectal cancer because it reduces the 20–25% probability of regional recurrences following complete surgical resection of stage II or III tumors, especially if they have penetrated through the serosa.
Cancers of the Anus Cancers of the anus account for 1–2% of the malignant tumors of the large bowel. Most such lesions arise in the anal canal, the anatomic area extending from the anorectal ring to a zone approximately halfway between the pectinate (or dentate) line and the anal verge. Carcinomas arising proximal to the pectinate line (i.e., in the transitional zone between the glandular mucosa of the rectum and the squamous epithelium of the distal anus) are known as basaloid, cuboidal, or cloacogenic tumors; about one-third of anal cancers have this histologic pattern.
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