Definition and Overview
Stomach or gastric cancer is an abnormal growth in the stomach, the hollow organ in the digestive tract where food is liquefied. It typically arises from the lining of the stomach, but can also arise from other components, such as the smooth muscle. Just like esophageal cancer, the most common type of stomach cancer is adenocarcinoma. Other types include lymphoma, gastric melanoma, and gastrointestinal stromal tumor, or GIST.
In recent years, there has been a decrease in the incidence of gastric cancer in the United States and other Western countries. However, it remains to be one of the leading causes of cancer death worldwide. It is the top 5 cause of cancer and is responsible for approximately 7% of cancer cases. It is common in Asia, specifically in Japan and Korea. Stomach cancer more commonly affects men than women, and usually affects the elderly population, usually those more than 70 years old. Gastric cancer in younger individuals tends to be more aggressive and have a worse prognosis. The estimated survival rate for gastric cancer in 5 years is approximately 20%.
Stomach Cancer Causes
Genetic factors are involved in the pathogenesis of stomach cancer. Abnormalities in the p53, COX-2, and CDH1 genes have been associated with this neoplasm. Individuals with a family history of gastric cancer are also at increased risk.
Aside from heredity and genetics, stomach cancer is also believed to be strongly influenced by environmental factors. Some studies have shown that when patients from an area where there is a high incidence of stomach cancer migrate to a region with a low incidence, the risk of stomach cancer decreases in the succeeding generations living in that area.
Diet seems to play an important role as well. An increased risk in the development of stomach cancer is seen in patients with a diet high in starch and smoked meat. Dietary nitrates found in cured meat may be a cause of stomach cancer. Nitrates in food are converted into nitrite, a carcinogen, in the stomach. In regions where there is a high incidence of gastric cancer, decreased intake of nitrate-rich food and increased intake of vitamins C and E have correlated with a decreased risk for the development of stomach cancer in the population.
Stomach cancer is also associated with chronic infection of Helicobacter pylori, a type of bacteria associated with chronic gastritis and the development of recurrent peptic ulcers. Approximately half of the population of the world is believed to be infected with this organism. Patients who have chronic infection are up to three times more likely to develop stomach cancer than those who are not infected. Greater than 60% of stomach cancer cases are related to H. pylori infection.
Smoking is also believed to contribute to the development of stomach cancer. An increase in risk of 40-80% can be seen in people who are heavy smokers. Stomach cancers in these patients are usually located in the upper area of the stomach.
Others with a higher risk of developing stomach cancer include patients with pernicious anemia, obese patients with gastroesophageal reflux disease or GERD, patients with chronic atrophic gastritis, immunocompromised individuals with AIDS, and patients with chronic myelocytic leukemia (CML).
Stomach Cancer Symptoms
Stomach cancer usually has non-specific symptoms, especially in the early stages of the disease; thus, gastric cancer is typically diagnosed in the advanced stages. One of the most common symptoms of stomach cancer is weight loss. Patients also frequently experience early satiety or feeling full even when eating only a small amount of food. Other gastrointestinal symptoms are also common, such as loss of appetite, vomiting, heartburn, bloating, indigestion and occasionally difficulty in swallowing. Abdominal discomfort or pain also occurs. Occult bleeding in the stool is common, but acute bleeding resulting in black tarry stools is not typical and usually occurs when the mass has already enlarged. Because stomach cancer is usually diagnosed late, some patients already present with symptoms indicating the spread of the disease to other organs of the body, such as difficulty in breathing.
The physical examination of a patient with stomach cancer is usually normal. However, some patients have palpable stomach tumor in the upper part of the organ. Some patients may also present with visible, enlarged nodes in the neck or abdomen.
Stomach Cancer Treatment
Seek consult if you are experiencing signs of stomach cancer. A gastroenterologist will be able to evaluate you thoroughly and can request for various examinations to diagnose your condition. If you are suspected of having stomach cancer, you will have to undergo an esophagogastroduodenoscopy or EGD. A scope with a camera is inserted into your mouth down to your stomach to check for any masses. A biopsy can be done in the same sitting to determine the presence of cancer cells. You may also have to undergo imaging tests, such as a CT scan, to determine the extent of the disease. If you are indeed discovered to have stomach cancer, your gastroenterologist may refer you to several other specialists, such as a general surgeon, a medical oncologist, and a radiation oncologist.
Surgery is the common treatment for stomach cancer. Gastric cancer in the early stages can be treated endoscopically, which is a minimally invasive type of procedure. For bigger tumors that are still resectable, patients should undergo a kind of surgery known as radical subtotal gastrectomy. The surgery involves the removal of the entire stomach tumor, including lymph nodes, with adequate margins. Other involved organs may have to be removed together with the tumor in the stomach. A selected group of patients with metastatic disease may also benefit from a palliative gastrectomy. In patients with advanced stages of the disease, surgery may also be performed to improve symptoms and quality of life.
Chemotherapy and radiation therapy have minimal proven benefit in the treatment of stomach cancer that has been adequately resected. However, these modalities of treatment are useful for palliative management and can help decrease the size of the mass and relieve the patient’s symptoms. Clinical trials are underway to determine the roles of chemotherapy and novel targeted therapy in stomach cancer.
Gastric Cancer Foundation. https://www.gastriccancer.org
Stomach (Gastric) Cancer – National Cancer Institute. https://cancer.gov/cancertopics/types/stomach