Tumors of the Gastrointestinal Tract


Chapter 143

Tumors of the Gastrointestinal Tract



Lindsey Law


Tumors of the gastrointestinal tract may be benign or malignant. It is essential that malignant tumors be identified as early as possible and treated appropriately. This chapter focuses on the common malignant neoplasms of the esophagus, stomach, small intestine, and colon; common benign tumors of the gastrointestinal tract are also discussed.



Tumors of the Esophagus


Definition and Epidemiology


Esophageal carcinoma is a malignant neoplasm of the esophagus. The two most common types of malignant neoplasms are adenocarcinoma and squamous cell carcinoma. Squamous cell carcinoma accounts for 95% of esophageal cancers worldwide, and adenocarcinoma accounts for 50% to 80% of esophageal cancers in the United States.1 Squamous cell carcinomas develop from cells in the proximal portion of the esophagus, and adenocarcinomas develop from glandular cells in the distal portion of the esophagus. Squamous cell carcinoma is more common in African Americans, whereas adenocarcinoma is more common in whites. Men are three times as likely as women to develop esophageal cancer. In the United States, the rates of squamous cell carcinoma have decreased among African-American men, whereas the rates of adenocarcinoma in white men have increased.1 The incidence of esophageal cancer increases with age. The majority of persons affected by esophageal cancer are aged 50 to 70 years, and approximately 40% of older adults with Barrett esophagus will develop adenocarcinoma of the esophagus. The prevalence of esophageal cancer is higher in northern China, South Africa, France, Iran, and parts of Asia.2 Survival rates are poor for persons with esophageal cancer. The overall survival rate is approximately 14%.3


Older age, male gender, drinking, smoking, and cancer of the head and neck are risk factors for the development of esophageal cancer. Nutritional deficiencies of vitamins and trace elements have also been implicated.4 The major risk factors for squamous cell esophageal carcinoma are chronic smoking and alcohol consumption, achalasia, and tylosis.5 The single most important risk factor for the development of adenocarcinoma of the esophagus is esophageal reflux leading to the premalignant condition of Barrett esophagus.5 Obesity is emerging as a significant risk factor for esophageal cancer, although a causal relationship has not been established.5



Pathophysiology


Esophageal cancers are usually related to squamous cell carcinoma or adenocarcinoma.6 The majority of esophageal tumors are located in the lower third of the esophagus (55%), but one tenth are found in the upper esophagus and these are usually squamous cell carcinomas.6 Esophageal adenocarcinomas arise in Barrett esophagus, a metaplasia of the distal esophagus occurring in association with long-term gastroesophageal reflux.6 The extensive lymphatic system of the esophagus allows cancers of the esophagus to spread locally and into adjacent mediastinal structures regardless of tumor type.7



Clinical Presentation


Dysphagia is the classic presenting symptom of esophageal carcinoma. This symptom indicates that the esophageal lumen has been reduced by at least half of its normal diameter.8 Other symptoms include anorexia, weight loss, and odynophagia with radiation to the back. Hoarseness results from tumor involvement of the recurrent laryngeal nerve, and a tracheoesophageal fistula may produce a chronic cough.8 The clinical features of esophageal adenocarcinoma are similar to those of squamous cell carcinoma, but it may also produce early satiety, nausea, vomiting, and bloating because of tumor encroachment into the stomach.



Physical Examination


Fixed supraclavicular, cervical, and axillary lymphadenopathies are signs of advanced disease. Both hepatomegaly secondary to metastatic disease and superior vena cava syndrome indicate a poor prognosis.7,8



Diagnostics


New-onset dysphagia should prompt an evaluation for an esophageal tumor. Diagnostic evaluation of the patient with a suspected esophageal carcinoma is a two-step procedure that begins with barium esophagography and is followed by upper gastrointestinal endoscopy with biopsy and cytologic tests.5 Barium esophagography and endoscopy are used in evaluating the primary tumor. Endoscopic ultrasound examination will help determine the extent of disease locally.5 A clinical examination, biochemical assay, chest x-ray examination, computed tomography (CT) scan, positron emission tomography–computed tomography (PET/CT) scan, radionuclide bone scan, ultrasonography, and guided fine-needle aspiration biopsy of lymph nodes may be useful in the evaluation of metastasis.5




Differential Diagnosis


In the adult patient with a new onset of progressive, solid dysphagia, the differential diagnosis includes esophageal squamous cell carcinoma, esophageal adenocarcinoma, adenocarcinoma of the gastric cardia, benign peptic stricture, corrosive stricture, and esophageal motor disorders such as achalasia and scleroderma. Symptoms of dysphagia, especially in a patient older than 45 years, mandate a complete evaluation to exclude esophageal carcinoma.




Management


Gastroenterologic, oncologic, and surgical consultations are critical for the evaluation of esophageal tumors. Surgical resection is the primary treatment of early-stage esophageal cancer. Chemotherapy with cisplatin and 5-fluorouracil plus radiation therapy with or without surgery may provide the best potential for cure in locally advanced disease.7 However, palliation for dysphagia may be the only realistic goal because most patients have incurable disease at the time of diagnosis. Palliation can be accomplished by peroral stenting through the stenosis and transendoscopic ablation of obstructing tumors by laser photocoagulation.


For advanced disease, esophagectomy provides superb palliation.9 Radiotherapy may provide palliation for patients who are not candidates for surgery.9


Systemic chemotherapy is a preferred method of palliation for metastatic disease. There are many chemotherapy agents available; however, there is not one particular regimen that is standard of care in the first-line setting.


Postoperative elevation of serum carcinoembryonic antigen (CEA) levels may be the first objective sign of recurrent disease and should prompt additional therapy, such as surgery or chemotherapy.10



Complications


Because of the distensibility of the esophagus, esophageal carcinoma tends to be silent until late in its course. Complications are usually related to mediastinal extension or esophageal narrowing and may include obstruction, hemorrhage, perforation, and fistula formation. Because the esophagus lacks a true serosa, cancer is often not contained at the time of diagnosis. The lungs and liver are the most common sites of hematogenous metastasis. Complications of esophageal resection include torsion or gangrene of the gastric, colonic, or jejunal pull-up; anastomotic leak; anastomotic stricture; subphrenic abscess; chylothorax; hemorrhage; wound infection and dehiscence; sepsis; dumping syndrome; vocal chord paralysis, and reflux esophagitis.



Patient and Family Education


Dietary instructions should be consistent with the degree of dysphagia experienced. Patients who have responded to therapy but continue to use alcohol and tobacco products during treatment demonstrate a poor response to treatment and an increased rate of local recurrence.9 Therefore, patients should be encouraged to discontinue the use of these products and should be provided with therapeutic interventions for alcohol and tobacco cessation.9,11



Health Promotion


Patients should be regularly questioned about the presence of heartburn or other signs of gastroesophageal reflux so that appropriate diagnostics and treatment can be initiated. Primary prevention of esophageal cancer includes avoidance of all tobacco products and of heavy alcohol consumption. It is also important to consume a diet that is rich in fruits and vegetables and to maintain a normal weight. With obesity, there can be increased acid reflux, thus multiplying the risk for adenocarcinoma of the lower esophagus and stomach.9,11



Tumors of the Stomach


Definition and Epidemiology


Gastric cancer is the second most common cause of cancer-related deaths worldwide. The prevalence of gastric cancer remains very high (70 per 100,000) in Japan, eastern Asia, eastern Europe, Chile, Colombia, and Central America.5 The incidence of gastric cancer in the United States has declined dramatically during the past 70 years.5 In this country, approximately 22,000 persons are diagnosed with gastric cancer each year, and about 11,000 people die of gastric cancer yearly.5 The decline in gastric cancer has been attributed to improved refrigeration and the reduced consumption of preserved foods.5 Gastric carcinoma occurs more often in African Americans, Hispanics, and Native Americans.5 Common benign tumors of the stomach include leiomyomas and epithelial polyps.


Helicobacter pylori is noted as the primary risk factor for gastric cancer.12 Other risk factors for gastric adenocarcinoma include chronic atrophic gastritis, pernicious anemia, and gastric polyps.4 Dietary risk factors include a decreased consumption of fruits and vegetables and an increased intake of salt, nitrates and nitrites, and smoked and poorly preserved foods.4 Genetic factors linked to gastric carcinoma include hereditary nonpolyposis colorectal cancer, familial polyposis, and first-degree relatives of patients with gastric cancer. A partial gastrectomy for peptic ulcer disease is also associated with an increased risk of gastric carcinoma.



Pathophysiology


Gastric cancer is divided into two histologic types, intestinal and diffuse.5 The intestinal type of gastric adenocarcinoma is characterized by distinct, large glands lined by columnar cells; it resembles intestinal cancer and is more common than the diffuse type.5 The diffuse type of gastric cancer is poorly differentiated, lacks a glandular structure, and is more aggressive.5 Gastric carcinomas spread by direct extension, lymphatic spread, hematogenous metastasis, and peritoneal seeding.



Clinical Presentation


Unexplained weight loss, upper abdominal pain, anorexia, nausea, and vomiting are the most common symptoms of advanced gastric carcinoma.4 The abdominal pain begins as insidious upper abdominal discomfort that ranges in intensity from a vague sense of postprandial fullness to a severe, steady pain. Other symptoms include change in bowel habits, dysphagia, melena, anemic symptoms, and hemorrhage.4



Physical Examination


Patients with advanced gastric cancer may be initially seen with cachexia, small bowel obstruction, epigastric mass, ascites, hepatomegaly, or lower extremity edema. Metastases may also manifest as an enlarged left supraclavicular lymph node (Virchow node) or an enlarged left anterior axillary lymph node, an enlarged periumbilical lymph node (Sister Mary Joseph node), an enlarged ovary (Krukenberg tumor), or a mass on the Blumer shelf on rectal examination.5



Diagnostics


Blood studies may reveal hypochromic, microcytic anemia secondary to iron deficiency. The stool is often positive for occult blood. Upper gastrointestinal endoscopy is the imaging modality of choice for stomach tumors because it allows direct visualization and biopsy of the tumor.5 Once the diagnosis of gastric cancer is confirmed, abdominal and chest CT scans along with endoscopic ultrasound examination are indicated to establish the invasiveness of the primary tumor and the extent of metastasis.5



Differential Diagnosis


The differential diagnosis for tumors of the stomach includes gastric lymphoma; leiomyosarcoma; carcinoid tumors; and gastric metastasis from the lung, breast, and melanoma. Kaposi’s sarcoma of the stomach, which may be present in patients with acquired immunodeficiency syndrome (AIDS), and hypertrophic gastropathy (Meniere disease) are also included in the differential diagnosis.



Management


Gastroenterologic, surgical, and oncologic consultations are essential for a patient with gastric cancer. Complete resection of the gastric carcinoma and adjacent lymph nodes offers the only chance for cure. A palliative resection should be considered for patients with advanced lesions who are initially seen with obstruction or bleeding.


In patients with locally advanced tumors or in those who are not surgical candidates secondary to comorbidities, combination chemotherapy plus radiation can be definitive. Pathologic complete response can be obtained in up to 30% of patients. Systemic chemotherapy is a preferred method of palliation for metastatic disease. There are many chemotherapy agents available; however, there is not one particular regimen that is standard of care in the first-line setting.


Obstruction and bleeding from large carcinomas of the gastric cardia can be managed by stent therapy, endoscopic laser therapy, or angiographic embolization.5

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Oct 12, 2016 | Posted by in CRITICAL CARE | Comments Off on Tumors of the Gastrointestinal Tract

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