Gastric cancer
Gastric cancer: Excerpt from Handbook of Diseases
Common throughout the world, gastric cancer affects all races. However, unexplained geographic and cultural differences in incidence occur; for example, mortality is high in Japan, Iceland, Chile, and Austria. In the United States, incidence has decreased 50% during the past 25 years, and the death rate from gastric cancer is one-third that of 30 years ago.
The decrease in gastric cancer incidence in the United States has been attributed, without proof, to the balanced American diet and to refrigeration, which reduces the number of nitrate-producing bacteria in food.
Incidence is highest in men over age 40. The prognosis depends on the stage of the disease at the time of diagnosis; overall, the 5-year survival rate is about 15%.
Causes
The cause of gastric cancer is unknown. This cancer is commonly associated with gastritis, chronic inflammation of the stomach, gastric ulcers, Helicobacter pylori bacteria, and gastric atrophy. Predisposing factors include environmental influences, such as smoking and high alcohol intake.
Genetic factors have also been implicated because this disease occurs more frequently among people with type A blood than among those with type O; similarly, it’s more common in people with a family history of such cancer.
Dietary factors include types of food preparation, physical properties of some foods, and certain methods of food preservation (especially smoking, pickling, and salting).
Classification
According to gross appearance, gastric cancer can be classified as polypoid, ulcerating, ulcerating and infiltrating, or diffuse. The parts of the stomach affected by gastric cancer, listed in order of decreasing frequency, are the pylorus and antrum (50%), the lesser curvature (25%), the cardia (10%), the body of the stomach (10%), and the greater curvature (2% to 3%).
Metastasis
Gastric cancer metastasizes rapidly to the regional lymph nodes, omentum, liver, and lungs by the following routes: walls of the stomach, duodenum, and esophagus; lymphatic system; adjacent organs; bloodstream; and peritoneal cavity.
Signs and symptoms
Early clues to gastric cancer are chronic dyspepsia and epigastric discomfort, followed in later stages by weight loss, anorexia, a feeling of fullness after eating, anemia, and fatigue. If the cancer is in the cardia, the first symptom may be dysphagia and, later, vomiting (typically coffee-ground vomitus). Affected patients may also have blood in their stools.
The course of gastric cancer may be insidious or fulminating. The patient typically treats himself with antacids until the symptoms of advanced stages appear.
Diagnosis
Diagnosis depends primarily on reinvestigations of persistent or recurring GI changes and complaints. To rule out other conditions that produce similar symptoms, a diagnostic evaluation must include the testing of blood, stools, and stomach fluid specimens.
Gastric cancer commonly requires the following studies for diagnosis:
❑ Barium X-rays of the GI tract, with fluoroscopy, show changes (a tumor or filling defect in the outline of the stomach, loss of flexibility and distensibility, and abnormal gastric mucosa with or without ulceration).
❑ Gastroscopy with fiber-optic endoscopy helps rule out other diffuse gastric mucosal abnormalities by allowing direct visualization and gastroscopic biopsy to evaluate gastric mucosal lesions.
❑ Endoscopy for biopsy and cytologic washings and photography with fiber-optic endoscopy provide a permanent record of gastric lesions that can later be used to determine the progress of the disease and the effect of treatment.
The following studies may rule out metastasis to specific organs: computed tomography scans, chest X-rays, liver and bone scans, and a liver biopsy.
Treatment
Surgery is commonly the treatment of choice. Excision of the lesion with appropriate margins is possible in more than one-third of patients. Even in patients whose disease isn’t considered surgically curable, resection offers palliation and improves potential benefits from chemotherapy and radiation therapy.
Surgery
The nature and extent of the lesion determine what kind of surgery is most appropriate. Common surgical procedures include subtotal gastrectomy and total gastrectomy.
When cancer involves the pylorus and antrum, gastrectomy removes the lower stomach and duodenum (gastrojejunostomy or Billroth II). If metastasis has occurred, the omentum and spleen may also have to be removed.
If gastric cancer has spread to the liver, peritoneum, or lymph glands, palliative surgery may include gastro-stomy, jejunostomy, or a total or subtotal gastrectomy. Such surgery may temporarily relieve vomiting, nausea, pain, and dysphagia while allowing enteral nutrition to continue.
Other treatments
Chemotherapy for GI cancers may help to control symptoms and prolong survival. Adenocarcinoma of the stomach has responded to several agents, including fluorouracil, carmustine, doxorubicin, cisplatin, methotrexate, and mitomycin.
Antiemetics can control nausea, which increases as the cancer advances. In the more advanced stages, sedatives and tranquilizers may be necessary to control overwhelming anxiety. Narcotics are necessary in many cases to relieve severe and unremitting pain.
Radiation therapy has been particularly useful when combined with chemotherapy in patients who have unresectable or partially resectable disease. It should be given on an empty stomach and shouldn’t be used preoperatively because it may damage viscera and impede healing.
Treatment with antispasmodics and antacids may help relieve GI distress.
Special considerations
❑ Before surgery, prepare the patient for its effects and for postsurgical procedures such as insertion of a nasogastric (NG) tube for drainage and I.V. lines.
❑ Reassure the patient who is having a subtotal gastrectomy that he may eventually be able to eat normally.
❑ Prepare the patient who is having a total gastrectomy for slow recovery and only partial return to a normal diet.
❑ Emphasize the importance of changing position every 2 hours and of deep breathing.
❑ After any type of gastrectomy, pulmonary complications may result and oxygen may be needed. Regularly assist the patient with turning, coughing, and deep breathing. Turning the patient hourly and administering narcotic analgesics may prevent pulmonary problems. Incentive spirometry may also be needed for complete lung expansion. Proper positioning is important as well: Semi-Fowler’s position facilitates breathing and drainage.
❑ After gastrectomy, little (if any) drainage comes from the NG tube because no secretions form after stomach removal. Without a stomach for storage, many patients experience dumping syndrome. Intrinsic factor is absent from gastric secretions, leading to malabsorption of vitamin B12.
Clinical tip After gastric surgery, don’t irrigate or check placement of the NG tube because this may cause pressure at the incision site and possible rupture.
❑ To prevent vitamin B12 deficiency, the patient must take a replacement vitamin for the rest of his life as well as an iron supplement.
❑ During radiation therapy, encourage the patient to eat high-calorie, well-balanced meals. Offer fluids, such as ginger ale, to minimize such adverse effects as nausea and vomiting.
❑ Patients who experience poor digestion and absorption after gastrectomy need a special diet: frequent feedings of small amounts of clear liquids, increasing to small, frequent feedings of bland food.
❑ After total gastrectomy, patients must eat small meals for the rest of their lives.
Clinical tip Some patients need pancreatin and sodium bicarbonate after meals to prevent or control steatorrhea and dyspepsia.
❑ Wound dehiscence and delayed healing, stemming from decreased protein, anemia, and avitaminosis, may occur. Preoperative vitamin and protein replacement can prevent such complications.
❑ Observe the wound regularly for redness, swelling, failure to heal, and warmth. Parenteral administration of vitamin C may improve wound healing.
❑ Vitamin deficiency may result from obstruction, diarrhea, or an inadequate diet. Ascorbic acid, thiamine, riboflavin, nicotinic acid, and vitamin K supplements may be beneficial.
❑ Aside from meeting caloric needs, nutrition must provide adequate protein, fluid, and potassium intake to facilitate glycogen and protein synthesis.
❑ Anabolic agents may induce nitrogen retention. Steroids, antidepressants, wine, and brandy may boost the appetite.
When all treatments have failed:
❑ Concentrate on keeping the patient comfortable and free from pain, and provide as much psychological support as possible.
❑ If the patient is going home, discuss continuing care needs with the caregiver or refer the patient to an appropriate home health care agency.
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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