Gastric cancer in the context of "Peptic ulcer"

The Epstein–Barr virus (EBV), also known as human herpesvirus 4 (HHV-4), is one of the nine known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. EBV is a double-stranded DNA virus. EBV is the first identified oncogenic virus, a virus that can cause cancer. EBV establishes a permanent infection in human B cells. It uncommonly causes infectious mononucleosis and is also tightly linked to many malignant diseases (cancers and autoimmune diseases). Various vaccine formulations have been tested in humans and other animals; however, none of them were able to prevent EBV infection, thus, no vaccine has been approved to date.

Infectious mononucleosis ("mono" or "glandular fever"), is characterized by extreme fatigue, fever, sore throat, and swollen lymph nodes. EBV is also associated with various non-malignant, premalignant, and malignant EBV-associated lymphoproliferative diseases such as Burkitt lymphoma, hemophagocytic lymphohistiocytosis, and Hodgkin's lymphoma; non-lymphoid malignancies such as gastric cancer and nasopharyngeal carcinoma; and conditions associated with human immunodeficiency virus such as hairy leukoplakia and central nervous system lymphomas. The virus is also associated with the childhood disorders of Alice in Wonderland syndrome and acute cerebellar ataxia and, by some evidence, higher risks of developing certain autoimmune diseases, especially dermatomyositis, systemic lupus erythematosus, rheumatoid arthritis, and Sjögren's syndrome. About 200,000 cancer cases globally per year are thought to be attributable to EBV. In 2022, a large study following 10 million active US military over 20 years suggested EBV as the leading cause of multiple sclerosis (MS), with a recent EBV infection causing a 32-fold increase in MS risk development.

Helicobacter pylori, previously known as Campylobacter pylori, is a gram-negative, flagellated, helical bacterium. Mutants can have a rod or curved rod shape that exhibits less virulence. Its helical body (from which the genus name Helicobacter derives) is thought to have evolved to penetrate the mucous lining of the stomach, helped by its flagella, and thereby establish infection. While many earlier reports of an association between bacteria and the ulcers had existed, such as the works of John Lykoudis, it was only in 1983 when the bacterium was formally described for the first time in the English-language Western literature as the causal agent of gastric ulcers by Australian physician-scientists Barry Marshall and Robin Warren. In 2005, the pair was awarded the Nobel Prize in Physiology or Medicine for their discovery.

Infection of the stomach with H. pylori does not necessarily cause illness: over half of the global population is infected, but most individuals are asymptomatic. Persistent colonization with more virulent strains can induce a number of gastric and non-gastric disorders. Gastric disorders due to infection begin with gastritis, or inflammation of the stomach lining. When infection is persistent, the prolonged inflammation will become chronic gastritis. Initially, this will be non-atrophic gastritis, but the damage caused to the stomach lining can bring about the development of atrophic gastritis and ulcers within the stomach itself or the duodenum (the nearest part of the intestine). At this stage, the risk of developing gastric cancer is high. However, the development of a duodenal ulcer confers a comparatively lower risk of cancer. Helicobacter pylori are class 1 carcinogenic bacteria, and potential cancers include gastric MALT lymphoma and gastric cancer. Infection with H. pylori is responsible for an estimated 89% of all gastric cancers and is linked to the development of 5.5% of all cases cancers worldwide. H. pylori is the only bacterium known to cause cancer.

Upper gastrointestinal bleeding (UGIB) is gastrointestinal bleeding in the upper gastrointestinal tract, commonly defined as bleeding arising from the esophagus, stomach, or duodenum. Blood may be observed in vomit or in altered form as black stool. Depending on the amount of the blood loss, symptoms may include shock.

Upper gastrointestinal bleeding can be caused by peptic ulcers, gastric erosions, esophageal varices, and rarer causes such as gastric cancer. The initial assessment includes measurement of the blood pressure and heart rate, as well as blood tests to determine the hemoglobin.

Cancer immunotherapy (immuno-oncotherapy) is the stimulation of the immune system to treat cancer, improving the immune system's natural ability to fight the disease. It is an application of the fundamental research of cancer immunology (immuno-oncology) and a growing subspecialty of oncology.

Cancer immunotherapy exploits the fact that cancer cells often have tumor antigens, molecules on their surface that can bind to antibody proteins or T-cell receptors, triggering an immune system response. The tumor antigens are often proteins or other macromolecules (e.g., carbohydrates). Normal antibodies bind to external pathogens, but the modified immunotherapy antibodies bind to the tumor antigens marking and identifying the cancer cells for the immune system to inhibit or kill. The clinical success of cancer immunotherapy is highly variable between different forms of cancer; for instance, certain subtypes of gastric cancer react well to the approach whereas immunotherapy is not effective for other subtypes.