Which histologic findings indicate gastric cancer?

Updated: May 21, 2019
  • Author: Elwyn C Cabebe, MD; Chief Editor: N Joseph Espat, MD, MS, FACS  more...
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Answer

Adenocarcinoma of the stomach constitutes 90-95% of all gastric malignancies. The second most common gastric malignancies are lymphomas. Gastrointestinal stromal tumors formerly classified as either leiomyomas or leiomyosarcomas account for 2% of gastric neoplasms (see Gastric Stromal Tumors). Carcinoids (1%), adenoacanthomas (1%), and squamous cell carcinomas (1%) are the remaining tumor histologic types. [3]

Adenocarcinoma of the stomach is subclassified according to histologic description as follows: tubular, papillary, mucinous, or signet-ring cells, and undifferentiated lesions.

Pathology specimens are also classified by gross appearance. In general, researchers consider gastric cancers ulcerative, polypoid, scirrhous (ie, diffuse linitis plastica), superficial spreading, multicentric, or Barrett ectopic adenocarcinoma.

Researchers also employ a variety of other classification schemes. The Lauren system classifies gastric cancer pathology as either type I (intestinal) or type II (diffuse). An appealing feature of classifying patients according to the Lauren system is that the descriptive pathologic entities have clinically relevant differences.

Intestinal, expansive, epidemic-type gastric cancer is associated with chronic atrophic gastritis, retained glandular structure, little invasiveness, and a sharp margin. The pathologic presentation classified as epidemic by the Lauren system is associated with most environmental risk factors, carries a better prognosis, and shows no familial history.

The second type, diffuse, infiltrative, endemic cancer, consists of scattered cell clusters with poor differentiation and dangerously deceptive margins. Margins that appear clear to the operating surgeon and examining pathologist often are determined retrospectively to be involved. The endemic-type tumor invades large areas of the stomach. This type of tumor is also not recognizably influenced by environment or diet, is more virulent in women, and occurs more often in relatively young patients. This pathologic entity is associated with genetic factors (such as E-cadherin), blood groups, and a family history of gastric cancer.

In 2013, researchers identified a possible third type of gastric adenocarcinoma. In an analysis of 248 gastric tumors using microarray-based gene-expression profiling, Lei et al found that this third subtype of gastric adenocarcinoma (which they termed the "metabolic" subtype; the other 2 subtypes are mesenchymal and proliferative) preferentially responds to 5-fluorouracil (5-FU). The researchers validated their findings in an independent set of 70 gastric tumors. [25, 26, 27] They believe that the preferential sensitivity of metabolic-subtype gastric cancers to 5-FU may be due to their significantly lower expression of thymidylate synthase and dihydropyrimidine dehydrogenase relative to the other 2 subtypes. [25]


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