Stomach Cancer – Causes, Symptoms, Diagnosis, Treatment and Prognosis
Stomach cancer is common throughout the world and affects all races, it is more common in men than women, and has its peak age range between 40 and 60 years old. Mortality is higher in Japan and Chile, presumably because of the different diets in those countries where they are less dependent on red meat.
Over the last 25 years the incidence of this type of cancer in the western world has decreased by 50% and the resulting death rate is less than a third of what it used to be but in less developed countries it is still a major cause of death, probably because in these countries by the time the disease is diagnosed (usually by means of a Barium meal) the stomach cancer is at a very advanced stage.
TYPES OF STOMACH CANCER
There are several different types of stomach cancer, some of which are very rare. The most common types start in the glandular cells of the stomach lining (adenocarcinomas), this is where stomach acid and digestive enzymes are made, and where most cancers start. When the tumor becomes more advanced, it can travel through the bloodstream and spread to organs such as the liver, lungs, and bones. Cancers that start in the lymphatic tissue (lymphoma), in the stomach’s muscular tissue (sarcoma) or in the tissues that support the organs of the digestive system (gastrointestinal stromal tumors) are less common and are treated in different ways.
SIGNS AND SYMPTOMS
Early clues to stomach cancer are chronic dyspepsia and epigastric discomfort, followed in later stages by weight loss, anorexia, a feeling of fullness after eating, anemia and fatigue. Blood in the stools may also be present and if the Cancer is in the Cardia (top) vomiting may occur.
The exact cause is unknown although the presence of the Helicopter pylori bacterium seems to be a major factor. Predisposing factors include environmental influences such as smoking and high alcohol intake. Because stomach cancer is more common amongst those with a family history and with people with type A blood, genetic factors are also implicated. Dietary factors, particularly methods of food preservation such as pickling, smoking or salting also have an influence on the prevalence.
Stomach cancer is diagnosed through an examination that may include an upper gastrointestinal (GI) series; endoscopy or gastroscopy where a thin flexible tube is passed down the throat so the doctor can see into the stomach, esophagus and upper part of the bowel Barium meals and Barium swallows. Because the 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.
The cancer can spread (metastasize) to the esophagus or the small intestine, and can extend through the stomach wall to nearby lymph nodes and organs. Metastasis occurs in 80-90% of individuals with stomach tumors, with a five year survival rate of 75% in those diagnosed in early stages and less than 30% of those diagnosed in late stages.
Although the cancer may be treated with surgery, radiation therapy, or chemotherapy, in many cases surgery is the treatment of choice. Even in patients whose disease is not considered surgically curable, resection offers a palliative effect and improves potential benefits from chemotherapy.
The nature and extent of the cancer determines what kind of surgery is most appropriate. Common surgical procedures include, partial and total removal of the stomach.
Antiemetics can control nausea, which increases as the cancer advances. In the more advanced stages, sedatives and tranquilizers may be necessary to control anxiety. Narcotics are commonly necessary to control sever and unremitting pain.
In some cases of advanced stomach cancer, a laser beam directed through an endoscope can vaporize most of the tumor and relieve obstruction without an operation.
Over the last few years there has been a considerable amount of research focusing on an imbalance in the body’s Redox homeostasis as a possible factor in the development of cancer. The theory has been postulated that if the Redox signaling system can be brought back into balance this may prove to be a viable therapy.
Stomach cancer is curable if detected early, but most people don’t seek medical help until the disease is quite advanced, possibly because symptoms occur late and are often vague and non-specific. Eating fresh fruits and vegetables that contain antioxidant vitamins (such as A and C) appears to lower the risk of stomach cancer. The rate of cancer is about doubled in smokers so the cessation of smoking is essential.
In the United States and most of the Western world, the 5-year survival rate ranges from 5-15%. In Japan, where stomach cancer often is diagnosed early, the 5 year survival rate is about 50%. Five year survival rates for more advanced stomach cancers range from, around 20% for those with regional disease to almost nil for those with distant metastases.
Treatment for metastatic stomach cancer can relieve symptoms and sometimes prolong survival, but long remissions are not common. The survival of inoperable stomach cancer is usually only a few months if untreated. With chemotherapy the average survival is about 12 months. If cancer is found before it has spread, the five-year relative survival rate is about 61%.