Could someone define what stomach cancer is?
I'm writing a paper on stomach cancer and I'm reading so many things on the disease and I have to define it and I'm getting confused could someone help me please?
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The stomach is a muscular pouch or bag-like structure located in the upper mid-abdomen. It is composed of several layers of tissue, including the inner lining called the mucosa, a sub-mucosa, a thick muscular wall, and the outer serosa.
Cancer in general occurs when cells of a particular organ mutate, causing those cells to divide in an uncontrolled fashion. Instead of simply dividing and reproducing themselves in a manner that replenishes cells that have died off, the mutant cells exhibit uncontrolled growth, and a tumor (mass) is formed. The tumor is a neoplasm (new growth), and in the case of stomach cancer (also called gastric cancer) it is a malignant neoplasm (meaning that it will progress and possibly kill the patient if unchecked).
The cause of gastric cancer is not known, however diets high foods that are pickled, smoked or salted seem to be a factor, as is smoking. Gastric cancer is uncommon in the USA, and much more common in Japan.
Any of the types of tissues in the stomach can become malignant neoplasm, however the most common cells doing this are the glandular cells comprising the mucosal lining of the stomach. In this case, the tumor is called an adenocarcinoma.
Less often, a tumor may arise in the immune tissue of the stomach, and is called malignant lymphoma.
Other types of unusual stomach cancer include carcinoid tumors that arise from the hormonal cells in the stomach, and gastrointestinal stromal tumors that come from the nervous tissue in the stomach.
The symptoms of gastric cancer vary with the stage of development of the tumor. Early cancers may merely cause indigestion. More advanced tumors can cause early satiety (sensation of full stomach) and weight loss.
Diagnosis is by X-ray with Barium swallow (to outline mucosal tumors or ulcers), computed tomography (CT Scan) and/or upper GI Endoscopy with biopsy. Endoscopy involves insertion of a flexible scope through the mouth into the stomach. Biopsy instruments are inserted through the opening of the scope, allowing biopsy and tissue diagnosis of the cancer type.
Stomach cancer is staged by doctors to help determine the appropriate treatment and to understand the prognosis (likely outcome with treatment).
Stage I: The tumor is confined to the gastric mucosa.
Stage II: The tumor has invaded into the muscular wall of the stomach, and may involve nearby lymph nodes.
Stage III: The tumor has invaded all layers of the stomach or has spread more extensively to lymph nodes.
Stage IV: Invasion is beyond the stomach to involve nearby structures, or there is distant metastasis to other organs such as liver, lungs and brain.
Among cancers, gastric cancer is one of the most lethal. This is because the tumor is often in an advanced stage before it is detected, plus the inherent aggressiveness of the cancer and an often poor response to therapy.
The first reference gives excellent general information on stomach cancer. It provides an especially good description of the symptoms of stomach cancer at various stages of the cancer’s development.
The second reference from the Mayo Clinic is an overview of stomach cancer. It covers signs and symptoms of the disease, cause, tests, diagnosis and treatment.
The stomach consists of five different layers: Inner layer or lining (mucosa), Submucosa, Muscle layer, Subserosa and the Outer layer (serosa). A stomach cancer can affect any of these parts of the stomach.
Cancers which start from the stomach wall usually infiltrate the muscularis mucosae, the submucosa, and finally the muscularis propria. From the stomach the cancer may spread into nearby organs, such as the liver, pancreas, esophagus, or intestine.
Cancer cells many a times break away to form new tumors that lead to increased damage. Irregular tubular structures, pluristratification, formation of multiple lumens and reduced stroma are also a result of stomach cancers.
If cancer cells are found in the tissue sample, the next step is to stage, or find out the extent of the disease. Various tests determine whether the cancer has spread and, if so, what parts of the body are affected. Because stomach cancer can spread to the liver, the pancreas, and other organs near the stomach as well as to the lungs, the doctor may order a CT scan, a PET scan, an endoscopic ultrasound exam, or other tests to check these areas. Blood tests for tumor markers, such as carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) may be ordered, as their levels correlate to extent of metastasis, especially to the liver, and the cure rate.
Infection by Helicobacter pylori is believed to be the cause of most stomach cancer while autoimmune atrophic gastritis, intestinal metaplasia and various genetic factors are associated with increased risk levels. The Merck Manual states that diet plays no role in the genesis of stomach cancer. However, the American Cancer Society lists the following dietary risks, and protective factors, for stomach cancer: "smoked foods, salted fish and meat, and pickled vegetables (appear to increase the risk of stomach cancer.) Nitrates and nitrites are substances commonly found in cured meats. They can be converted by certain bacteria, such as H. pylori, into compounds that have been found to cause stomach cancer in animals. On the other hand, eating fresh fruits and vegetables that contain antioxidant vitamins (such as A and C) appears to lower the risk of stomach cancer." A December 2009 article in American Journal of Clinical Nutrition found a statistically significant inverse correlation between higher adherence to a Mediterranean Dietary Pattern and stomach cancer.
In more detail, H. pylori is the main risk factor in 65–80% of gastric cancers, but in only 2% of such infections. Approximately ten percent of cases show a genetic component. Some studies indicate that bracken consumption and spores are correlated with incidence of stomach cancer, though causality has yet to be established
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