In our body, healthy cells grow and divide in an orderly way. This process is controlled by DNA, which is a genetic material containing instructions for every chemical process in our body. Some DNA genes promote cell division, others slow it down or program cells to die at the right time. While other genes control processes that help repair DNA.
When DNA is damaged these genes do not function correctly, causing cell growth out of control and eventually form a tumor- a malignant mass. Although the causes of many types of cancers are not fully understood, research has made real progress in determining the factors that destroy the DNA of stomach cells and how these damages lead to cancer.
Infection by Helicobacter Pylori (H P) About 2/3 of the world's population is infected with such a bacterium that lives deep in the mucosal layers of the stomach. It is thought that this bacterium spreads from person to person, through the fecal-oral route, or through contaminated water. Infection by HP often occurs in childhood and can last a lifetime if not treated.
Now, HP infection is recognized as the main cause of stomach ulcers, in about 80% of cases but can also be the main cause of stomach cancer. According to the World Health Organization, half of the new annual cases of stomach cancer are attributed to infection by Helicobacter Pylori. Having an ulcer does not necessarily put you at a high risk for stomach cancer, but having an infection with Helicobacter Pylori, does.
This happens because prolonged infection causes cellular inflammation which leads to precancerous changes in the stomach. One of these changes is atrophic gastritis, a condition in which acid-producing cells are destroyed. It is thought that low acid levels prevent cancer-causing toxins through their destruction or expulsion from the stomach.
Nitrates and nitrites These are natural chemical compounds that appear when bacteria break down nitrogen. Nitrates are used in many meat processing procedures. In our stomach, many bacteria, including HP, convert nitrates to nitrites, another nitrogenous chemical base. Nitrites are used in some meat-containing foods like hamburgers, bacon.
Nitrites combine with other nitrogen-containing substances to form N-nitroso compounds in the stomach, which are powerful carcinogens and are known as causes of stomach cancer.
Tobacco and alcohol abuse Together, they irritate the stomach and can cause cancer of the upper part of the stomach to the esophagus.
Smoked, pickled, and red meat foods Before the invention of the refrigerator, foods were preserved through smoking, salting, or pickling and frying. Preserved foods contain large amounts of nitrites and nitrates, which in our stomach are converted into cancer-causing compounds. Countries where a lot of smoked or pickled meat or fish is consumed, like Japan, have a high risk of stomach cancer. Likewise, a diet high in red meat (veal, beef, lamb) especially used as barbecue, is linked to stomach cancer.
Low socio-economic level It is thought that this is related to the spread rate of HP infection in developing countries.
The common and earliest sign of malignant and benign stomach tumors is microscopic internal bleeding, which is only detected by the fecal occult blood test. If bleeding continues, with the loss of red blood cells, this leads to anemia and the appearance of fatigue.
When cancer is very advanced, signs and symptoms such as:
But having one or more of these signs does not mean you have stomach cancer. There are other diseases, such as peptic ulcers, that can cause such signs.
The stomach is like a muscular bag, located in the upper left part of the abdomen, below the ribs. In an average adult age, the stomach has the size of a small pumpkin, but it can stretch from the sides to hold about 1 gallon of food and liquids. When empty, the stomach is contracted in itself and stretches after eating or drinking.
Although the stomach plays a major role in digestion, the actual digestive process begins with the mouth, where saliva begins the breakdown of carbohydrates and fats. From here, food passes into the esophagus, a 25 cm long tube that connects the throat to the stomach. At the end of the esophagus is a muscular valve (lower esophageal sphincter) that relaxes to allow the passage of food into the stomach.
The walls of the stomach are bordered by three strong muscular plates which chop the food into smaller pieces and mix them with enzymes and acid produced by the glands inside the stomach.
Hydrochloric acid is so corrosive that it can etch iron. On the other hand, the delicate tissues of the stomach are protected from this powerful acid by a thin layer of mucus, like gel, that lines the stomach.
As food in the stomach is broken down and mixed, it is the muscular contractions of the stomach that push it towards the pyloric valve, which allows passage to the upper part of the small intestine: the duodenum.
It takes 3-4 hours for the stomach to empty after eating, depending on the diet. Foods high in fat require more time to empty the stomach.
Most stomach tumors originate from glandular cells that line the stomach and these tumors are called adenocarcinomas. Sometimes the tumor can develop from the stomach's lymphatic tissue - lymphoma, or from muscle - sarcoma. About 3% of stomach tumors are carcinoid tumors that originate from hormone-producing cells of the stomach.
Carcinoid tumors metastasize less, while other tumors spread through growth in the stomach, esophagus, and in the small intestine. The tumor can also spread through the walls of the stomach, into the lymph nodes eventually spreading to other organs such as liver, pancreas, intestine, etc.