Gastric Adenocarcinoma

Key Features

Essentials of Diagnosis

• Dyspeptic symptoms with weight loss in patients age > 40

• Iron deficiency anemia; occult blood in stools

• Abnormality on upper gastrointestinal series or endoscopy

General Considerations

• There are two main histologic variants of gastric cancer

  • Intestinal-type

  • Diffuse

• Intestinal-type gastric cancer resembles intestinal cancers in forming glandular structures

  • Accounts for 70–80% of cases

  • Occurs twice as often in men as women

  • Primarily affects older people (mean age 63 years)

  • More strongly associated with environmental factors

• Diffuse gastric cancer is poorly differentiated, has signet-ring cells, and lacks formation of glandular structures

  • Accounts for 20–30% of cases

  • Affects men and women equally

  • Occurs more commonly in young people

  • Not as strongly related to Helicobacter pylori infection

  • Has a worse prognosis than the intestinal type

  • Most diffuse gastric cancers are attributable to acquired or hereditary mutations in the genes regulating the E-cadherin cell adhesion protein

• In addition to the hereditary diffuse gastric cancer, there are other hereditary cancer predisposition syndromes that account for 3–5% of gastric cancers

  • Lynch syndrome

  • Juvenile polyposis syndrome

  • Peutz-Jeghers syndrome

  • Familial adenomatous polyposis

• Most gastric cancers arise in the body and antrum

• Chronic H pylori gastritis is the major risk factor

• Other risk factors for intestinal-type gastric cancer

  • Pernicious anemia

  • Partial gastric resection > 15 years previously

  • Smoking

  • Diets that are high in nitrates or salt and low in vitamin C

Demographics

• Gastric adenocarcinoma is the most common cancer worldwide

• Incidence in the United States has declined rapidly over last 70 years

• In the United States, there were an estimated 27,600 new cases and 11,010 deaths in 2020

• Incidence is higher in Asian Americans, Hispanics, African Americans and American Indian/Alaska Natives

Clinical Findings

Symptoms and Signs

• Generally asymptomatic or nonspecific symptoms until advanced disease

• Dyspepsia, vague epigastric pain, anorexia, early satiety, and weight loss

• Acute upper gastrointestinal bleeding with hematemesis or melena

• Postprandial vomiting suggests pyloric obstruction

• Progressive dysphagia suggests lower esophageal obstruction

• Physical examination rarely helpful

• Gastric mass is palpated in < 20%

• Signs of metastatic spread include

  • Left supraclavicular lymph node (Virchow node)

  • Umbilical nodule (Sister Mary Joseph nodule)

  • Rigid rectal shelf (Blumer shelf)

  • Ovarian metastases (Krukenberg tumors)

Differential Diagnosis

• Benign gastric ulcers

• Lymphoma

• Ménétrier disease

Diagnosis

Laboratory Tests

• Iron deficiency anemia or anemia of chronic disease

• Liver biochemical test abnormalities, particularly elevation of alkaline phosphatase, if there is metastasis to liver

• Tumor markers

  • Do not have established clinical validity in screening, diagnosis, or management of gastric cancer

  • However, can assist in monitoring treatment response when checked serially

Imaging Studies

• Upper gastrointestinal ...