Gastric Cancer: Introduction, Pathology, Epidemiology

Abstract

astric carcinoma is a malignant disease, which starts in the stomach. Despite declining incidence still remains the second cause of death of all malignancies worldwide. It is a major health problem for two reasons: In Asia, East Europe and developing countries the incidence decreases slowly. In USA and West Europe although incidence decreases sharply, mortality of diagnosed gastric cancer remains high. Adenocarcinoma of the stomach still remains a major health problem. There has been an decrease in incidence of this cancer worldwide but the degree of this reduction varies considerably among different geographical areas. 1. In USA and West Europe gastric cancer decreases dramatically in the last 50 years. In USA only 21,700 new gastric cancer cases are expected in 2001. However, despite advances in research and current treatment improvements, mortality of diagnosed gastric cancer remains very high. 2. In China (1,3 billion population), Japan, Korea and other East countries the decrease in incidence is much slowly and gastric cancer remains one of the most common malignancy and a leading cause of death from cancer. 3. In developing countries the decrease in incidence is also slow. The world's population is expected to increase from the current 6.1 billion to 9.3 billion during the next 50 years (United Nations Population Division) with Africa and Asia experiencing the greatest population growth. Since gastric cancer decreases there slowly, is expected an increased number of new cases in developing countries and Asia. The challenge of controlling the disease in these areas can not obviously resolved by endoscopic screening for early detection or sophisticated staging with subsequent tailored multidisciplinary approach which appear completely unrealistic now or in the near future. A rethinking about effective management strategy of the disease is needed. The stomach is a sack-like organ between esophagus (a tube-shaped organ that carries food through the neck and chest to the stomach) and duodenum (first part of the small intestine). The stomach holds food and mixed it by secreting gastric juice into a thick fluid called chyme, which is then emptied into the duodenum. The stomach is divided into three different sections. The upper third, proximal stomach, closed to the esophagus is consisted of gastroesophageal junction (cardia) and fundus, the middle third of the stomach, the body and the lower portion (closed to the intestine) is the distal stomach consisted of the antrum and pylorus. Pylorus acts as a valve to control emptying of the stomach contents into the duodenum. The stomach wall includes from the inner to out lining 4 layers, the mucosa, submucosa, muscularis propria, subserosa and serosa). The stomach has two curves, the lesser and greater curves, in which is attached the lesser and greater omentum respectively. Other organs next to the stomach, apart of esophagus and duodenum, are the colon, liver, spleen, and pancreas. How does gastric carcinoma grow and spread? Cells divided, grow and accumulated form tumors. Both benign and malignant tumors grow in an uncontrolled way. But it is only cells of malignant tumors that invade surrounding tissues, travel in blood and lymphatic systems and home into distant organs where they form secondary tumors (metastasis). Malignant primary gastric cancer cells at first confined into the mucosal layer (intra-mucosal cancers) and after a rather long natural history progress infiltrating the other layers of the wall stepwise (submucosa, muscularis propria, subserosa, serosa). When at diagnosis the cancer invasion is confined to mucosa or submucosal layer is defined as early gastric cancer (EGC), whereas invasion into muscularis propria or beyond it is defined as advanced gastric cancer Gastric Breast Cancer 2002; 1(1): 1-3