الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Gastric carcinoma occurs worldwide with a variable distribution from country to country and ranks the fourth in order of global cancer incidence, combining both sexes. Gastric adenocarcinoma represents 90% of all gastric cancers. Microscopic examination of gastric adenocarcinomas shows a marked variation in their structure which is attributed to the complex nature of the normal gastric mucosa with its varied cell types as well as its proneness to undergo metaplasia to an intestinal type of epithelium.
The intestinal-type is more frequent and represents the dominant histological type in high risk areas suggesting environmental influences. The intestinal-type gastric carcinoma develops, over many years or even decades, through a sequence of events whereby the normal gastric mucosa is affected by chronic gastritis followed by glandular atrophy, intestinal metaplasia then dysplasia prior to the onset of cancer. It is well established that H. Pylori is likely involved early in the gastric neoplasia sequence and that additional risk factors are needed for progression. In contrast, the diffuse-type has not been related to precursor lesions and has a high association with familial occurrence.
Worldwide, gastric carcinoma has a dismal prognosis. It ranks second as a cause of cancer-related death in the world, being surpassed only by lung cancer. One of the most important reasons for such high mortality seems to be delayed consultation and diagnosis. Most patients are seen first with the disease in the late stage. At this point, most have lymph node and liver metastases, which make treatment even more complex. The 5-year survival rate in advanced stages is extremely poor and generally, it is less than 20%. On contrary, when early diagnosis is successful, there is a more better prognosis with 5-year survival rate rises up to 90%. ErbB2 (HER2) belongs to the erbB (HER) receptor family of type I receptor tyrosine kinases (RTKs). The erbB receptor family consists of the epidermal growth factor receptor (EGFR), erbB2 (HER2/neu), erbB3 (HER3), and erbB4 (HER4). Her2/neu is arguabily one of the most important receptor families in the context of development and tumorigenesis. Abnormal expression and/or aberrant activation of the erbB receptors have been demonstrated in a wide variety of human cancers. The rate of HER2 positivity in gastric cancer is estimated to be between 40% and 62%. Her 2 is considered positive when there is strong or moderate complete, lateral or basolateral staining reaction of tumor cells. Patients with Her2 positive gastric cancer can has great benefit from treatment with trastuzumab (Herceptin). Conclusion: Pathological diagnosis of different types of gastric carcinomas must be performed carefully with the application of diagnostic criteria of WHO classification taking into consideration that the typing of any particular tumor being based on its predominant pattern and is accurate only for the material examined.