Final answer:
Most gastric cancers are found in the pyloric antrum region of the stomach, near the greater curvature. The pyloric antrum is part of the pylorus, which is one of the four main regions of the stomach. Helicobacter pylori infection is closely associated with the risk of developing gastric cancer.
Step-by-step explanation:
Most gastric cancer is found in the pyloric antrum region of the stomach. The stomach is anatomically divided into four major regions: the cardia, the fundus, the body, and the pylorus. The pyloric antrum is the wider part of the pylorus, located near the greater curvature of the stomach, which is the most common site for the development of gastric cancer. The additional layers of muscles in the stomach, such as the inner oblique smooth muscle layer, provide the stomach with its ability to mix and churn food.
The role of the harmful, gram-negative bacterium Helicobacter pylori is significant in relation to stomach cancer, as it can survive the acidic environment of the stomach and is associated with an increased risk of developing the disease. However, not everyone infected with H. pylori will develop stomach cancer, as the prevalence of infection is much higher than the incidence of the cancer itself.