The stomach is a sac-like organ located in the upper abdomen between the esophagus and small intestine. It is part of the digestive system, functioning in the storage and digestion of food through the secretion of gastric juices. After leaving the stomach, partly-digested food passes into the small intestine and then into the large intestine.
The development of stomach cancer, also referred to as gastric cancer, usually occurs as a result of chronic inflammation. This can be due to both external and internal risk factors. A risk factor is anything that increases your risk of getting a disease. Risk factors for the development of gastric cancer include the following:
• Having any of the following medical conditions:
- Helicobacter pylori (H. pylori) infection of the stomach.
- Chronic gastritis (inflammation of the stomach).
- Pernicious anemia.
- Intestinal metaplasia (a condition in which the normal stomach lining is replaced with the cells that line the intestines).
- Familial adenomatous polyposis (FAP) or gastric polyps.
• Eating a diet high in salted, smoked foods and low in fruits and vegetables.
• Eating foods that have not been prepared or stored properly.
• Being over the age of 55 or male.
• Smoking cigarettes.
• Having a mother, father, sister, or brother who has had stomach cancer.
According to the National Cancer Institute (NCI), approximately 760,000 cases of stomach cancer are diagnosed worldwide and more than 24,000 cases are diagnosed in the United States each year. Incidence is highest in Japan, South America, Eastern Europe, and parts of the Middle East. Worldwide, stomach cancer is the second leading cause of cancer-related deaths. The overall prognosis of stomach cancer is poor because detection rarely occurs at the preclinical stage.
Diagnosis of stomach cancer involves taking a detailed medical history and performing a physical examination. Because of the size of the stomach, early symptoms are often non-specific and physical findings are not present until the advanced stages of disease. Symptoms in the early stages of gastric cancer include indigestion, stomach discomfort, a bloated feeling after eating, mild nausea, loss of appetite, or heartburn. In more advanced stages of gastric cancer patients may present with more intense stomach pain, vomiting, difficulty swallowing, weight loss for no known reason, blood in the stool, or a palpable mass on physical exam.
Upper Gastrointestinal Endoscopy (EGD) is the gold standard procedure for the detection and diagnosis of gastric cancer. In this procedure an endoscope (a thin, lighted tube containing a camera) is passed through the mouth and down the throat examining the inside of the esophagus, stomach, and duodenum (first part of the small intestine) to check for abnormal areas. Any unusual masses, protrusions, or ulcerations can be biopsied and sent for pathological analysis to determine if cancer cells are present.
Once the diagnosis of gastric cancer has been made, the progression of the extent of disease needs to be determined prior to any interventional treatment. This is done through a process called Staging. Once doctors have adequately staged the cancer and know the extent to which it has spread to other parts of the body, they can decide on the best course of treatment. CT Scans and PET Scans have been used for staging to detect the spread of disease to distant parts of the body. Recently, Endoscopic Ultrasound (EUS) has been used in assessing depth of tumor invasion, involvement of regional lymph nodes, or invasion of adjacent organs. Endoscopic Ultrasound allows for a more precise preoperative assessment of the tumor stage and permits the identification of the subset of patients who are candidates for preoperative chemoradiation therapy.
Surgery for Gastric Cancer
The extent of surgery for the treatment of stomach cancer depends on the extent of the disease. Endoscopic mucosal resection may be used to treat early stomach cancer (tumors smaller than 3 cm that have not invaded the innermost layer of the stomach lining called the submucosa). This procedure involves removing only the tumor and surrounding tissue.
Gastrectomy is the most common treatment for stomach cancer. In this surgery, the entire stomach (total gastrectomy) or part of the stomach (partial or sub-total gastrectomy) is removed. Parts of nearby tissues or organs (e.g., the spleen) may also be removed if involved with tumor. Surrounding lymph nodes are also removed.
Following total gastrectomy, the esophagus is attached directly to the small intestine. When a partial or sub-total gastrectomy is done, the remaining stomach is attached to the small intestine. The connection between these organs is called an anastomosis.
Like any major surgery patients may experience postsurgical pain, weakness, fatigue, and loss of appetite following surgery for gastric cancer. Recovery from the procedure varies depending on the patient's age and overall health, the type of surgery, and the stage of the disease.
Removal of a large part or all of the stomach usually requires permanent alterations in diet. Patients often must eat more frequently, eat smaller meals, reduce their sugar intake, and increase their intake of fat and protein. If a small section is removed, patients may be able to gradually return to previous eating habits.
Radiation therapy
Radiation therapy uses high-powered beams of energy to kill cancer cells. The energy beams come from a machine that moves around you as you lie on a table. Radiation therapy can be used before surgery (neoadjuvant radiation) to shrink a stomach tumor so it's more easily removed. Radiation therapy can also be used after surgery (adjuvant radiation) to kill any cancer cells that might remain around your stomach to prevent local recurrence. Radiation is often combined with chemotherapy. In cases of advanced cancer, radiation therapy may be used to relieve side effects caused by a large tumor.
Chemotherapy
Chemotherapy is a drug treatment that uses chemicals to kill cancer cells. Chemotherapy drugs travel throughout your body, killing cancer cells that may have spread beyond the stomach. Chemotherapy can be given before surgery (neoadjuvant chemotherapy) to help shrink a tumor so it can be more easily removed. Chemotherapy is also used after surgery (adjuvant chemotherapy) to kill any cancer cells that might remain in the body. Chemotherapy is often combined with radiation therapy. Chemotherapy may be used alone in people with advanced stomach cancer to help relieve signs and symptoms.
Recent studies have shown that the combination of preoperative radiation and chemotherapy in patients with locally advanced stomach cancer leads to an increase in the likelihood of surgical resection, and an improvement in disease free and overall survival. The addition of radiation and chemotherapy postoperatively has also been shown to decrease tumor recurrence and positively affect patient survival.
Overall prognosis depends on the stage of the disease. Stomach cancer metastasizes to distant parts of the body in as many as 80% of cases, resulting in a very poor prognosis. In Japan, where stomach cancer is often diagnosed early, the 5-year survival rate is about 50%. In the United States and most of the Western world, the 5-year survival rate ranges from 5-15%.
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