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Key Clinical Updates in Gastric Adenocarcinoma
Triplet chemotherapy for resectable gastric cancer is recommended for patients who are fit but is associated with more toxicity than doublet chemotherapy.
The development of immunotherapy represents a promising strategy in a selected patients with locally advanced and metastatic gastric cancer. Testing for microsatellite instability-high (MSI-H), mismatch repair deficiency (dMMR), PD-1, and PD-L1 is recommended in advanced disease to identify tumors that may respond to immunotherapy.
ASGE Standards of Practice Committee; Jue TL et al. Gastrointest Endosc. [PMID: 33168194]
de Steur WO et al; CRITICS investigators. Ann Oncol. [PMID: 33227408]
Kawazoe A et al. Jpn J Clin Oncol. [PMID: 33241322]
Ng SP et al. Ann Surg Oncol. [PMID: 33689079]
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ESSENTIALS OF DIAGNOSIS
Dyspeptic symptoms with weight loss in patients over age 40 years.
Iron deficiency anemia: occult blood in stools.
Abnormality detected on upper GI series, abdominal CT endoscopy; diagnosis established by endoscopic biopsy.
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GENERAL CONSIDERATIONS
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Gastric adenocarcinoma is the third most common cause of cancer death worldwide. Its main risk factors include increasing age, male gender, non-White race, smoking, and Helicobacter pylori infection. Chronic H pylori gastritis is the strongest risk factor, increasing the relative risk 3.5- to 20-fold.
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The incidence of gastric adenocarcinoma has declined rapidly over the last 70 years, especially in Western countries, perhaps attributable to changes in diet (more fruits and vegetables), increased food refrigeration (allowing more fresh foods and less salted, smoked, and preserved foods), reduced toxic environmental exposures, and a decline in H pylori infections.
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In the United States in 2022, gastric cancer will account for 1.5% of all new cancers (with an estimated 26,380 incident cases [15,900 men and 10,480 women]) and an estimated 11,090 deaths). In the United States, gastric cancer incidence is higher in Black (10 per 100,000), Native (including Native Alaskans) (9.9 per 100,000), Asian and Pacific Islander (9.7 per 100,000), and Latinx (9.5 per 100,000) Americans, than in White (5.3 per 100,000) Americans. The incidence of gastric cancer remains high (62 per 100,000 men) in Japan and many developing regions, including eastern Asia, Eastern Europe, Chile, Colombia, and Central America.
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There are two main histologic variants of gastric cancer: “intestinal-type” (which resembles intestinal cancers in forming glandular structures) and “diffuse” (which is poorly differentiated and lacks glandular formation).
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The incidence of intestinal-type gastric cancer has declined significantly, but it is still the more common type (70–80%); it occurs twice as often in men as women and primarily affects older people (mean age 68 years) and is more strongly associated with environmental factors. It is estimated that 60–90% of cases may be attributable to H pylori. It is believed to arise through a gradual, multi-step progression from inflammation (most commonly due to H pylori), to atrophic gastritis, to intestinal metaplasia, and finally to dysplasia and cancer. Other risk ...