STOMACH CANCER - Risk Factors, Cancer Staging, Clinical Manifestations, Diagnostic Evaluations, Management and Prevention
Stomach cancer, also called gastric cancer, begins when cells in the stomach become abnormal and grow uncontrollably. These cells form a growth of tissue, called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). Cancer can begin in any part of the stomach, and it can spread to nearby lymph nodes and other areas of the body, such as the liver, bones, lungs and a woman’s ovaries.
Most (85%) cases of gastric cancer are adenocarcinomas that occur in the lining of the stomach (mucosa). Approximately 40 % of cases develop in the lower part of the stomach (Pylorus); 40% develop in the middle part (body); and 15% develop in the upper part (cardia). In about 10% of cases, cancer develops in more than one part of the organ. Other types of stomach cancer include squamous cell carcinoma, lymphoma, stromal tumors (cancer of the muscle or connective tissue of the stomach wall), and carcinoid tumors (cancer of the hormone-producing cells of the stomach). Most stomach cancers start in the mucosa. The cancer can grow deeper and infect the other layers. As it grows deeper, the outlook for a cure gets worse.
Metastases through the bloodstream can spread to the liver, lungs, bone and brain. Metastases are also found in the lining of the abdominal cavity (peritoneum) and around the rectum.
- Infection with the Helicobacter pylori bacterium, which may lead to chronic inflammation of the inner layer of the stomach and possibly precancerous changes; recent research has shown that antibiotic treatment may reduce the risk of stomach – particularly stomach lymphoma – in people infected with this bacterium.
- A diet high in consumption of smoked and salted foods, such as smoked fish and meat and pickled vegetables; conversely, eating a diet high in fruits and vegetables (particularly those high in beta-carotene and vitamin C can decrease stomach cancer risk.
- High consumption of red meat; studies show that eating red meat more than 13 times per week can double the risk of stomach cancer
- Smoking and alcohol abuse
- Previous stomach surgery, such as removal of stomach tissue in patients with ulcers
- Pernicious anemia, a severe inability to produce red blood cells, due to a deficiency of vitamin 12
- Menetrier’s disease, a very rare condition associated with large folds in the stomach and low production of stomach acids
- Blood type A (for unknown reasons)
- Genetic (hereditary) risk factors include hereditary nonpolyposis colon cancer (HNPCC) syndrome and Li-Fraumeni syndrome (conditions that result in a predisposition to cancer), familial adenomatous polyposis (FAP)
- Family history of stomach cancer
- Stomach polyps
- Obesity: Excess body weight increases a man’s risk of developing stomach cancer. It is not clear whether obesity increases a woman’s risk of stomach cancer
- Age: most cases of stomach cancer occur in people over age 55
- Gender: men have twice the risk of developing stomach cancer as women
- Lack of physical activity: a lack of physical activity may increase the risk of stomach cancer
GASTRIC CANCER STAGING
Stage 0: Cancer has just begun to affect the inner stomach
Stage I: Cancer has begun to penetrate toward the outer layer of stomach. Nearby lymph nodes may be involved
Stage II: Cancer has progressed farther through tissue layers of stomach or more distant lymph nodes may be involved.
Stage III: Cancer has penetrated all tissue layers of stomach or distant lymph nodes may be involved.
Stage IV: Cancer has affected nearby organs and tissues. Cancer may even have been carried through the lymph system to distant parts of the body. This is known as metastasis.
Recurrent: Patient with previous gastric cancer was free, but cancer returned.
Stomach Cancer is often asymptomatic or causes only nonspecific symptoms in its early stages. By the time symptoms occur, the cancer has often reached an advanced stage. Stomach cancer can cause the following signs and symptoms:
- Discomfort or pain in the stomach area
- Difficulty swallowing
- Nausea and vomiting
- Weight loss
- Feeling full or bloated after a small meal
- Vomiting blood or having blood in the stool
- Gastrointestinal bleeding
- Indigestion or heartburn
- Loss of appetite (anorexia)
- Nausea and vomiting
- Diarrhea or constipation
- Iron deficiency anemia
- DIAGNOSTIC EVALUATIONS
Diagnosis of stomach cancer involves taking a medical history and performing a physical examination and laboratory tests. Tests may include fecal occult blood test, complete blood count (CBC), upper GI series (also called barium swallow), gastroscopy, and imaging tests.
- Physical Examination: There are few specific findings on a physical examination, and they generally indicate an advanced tumor. Some findings might be: Enlarged lymph nodes above the left collarbone(supraclavicular node), Nodal masses around the rectum, inside the navel or in the abdomen (involving the ovary), enlarged liver (hepatomegaly) and increased fluid intake in the abdomen (ascites).
- Fecal Occult Blood Test: FOBT is used to detect microscopic blood in the stool, which may indicate stomach or other GI cancers (e.g., colorectal cancer).
- Blood and Others Test: Complete blood count (CBC) is a simple blood test used to measure the concentration of white blood cells, red blood cells and platelets. CBC may indicate anemia from gastrointestinal bleeding, eerum chemistry profile to evaluate abnormal liver and bone chemistry enzymes, including tests for elevated levels of carcinoembryonic antigen (CEA) and levels of serum ferritin to indicate iron deficiency and analysis of gastric acid to detect achlorhydria.
- Barium Swallow: In an upper GI series, or barium swallow, the patient drinks a thick, chalky liquid (barium) that coats the esophagus and stomach and makes it easier to detect abnormal areas on x-ray. In double-contrast barium swallow, air is blown into the esophagus and stomach to help the liquid coat the wall of the organs more thoroughly.
- Laparoscopy: A surgeon makes small incisions (cuts) in abdomen. The surgeon inserts a thin, lighted tube (laparoscope) into the abdomen. The surgeon may remove lymph nodes or take tissue samples for biopsy.
- Gastroscopy: In gastroscopy, the physician inserts a thin tube that contains a light and camera (called a gastroscope) through the mouth and esophagus and into the stomach (fiberoptic endoscopy). The gastroscope allows the physician to see the inside of the stomach. Small instruments can be passed through the gastroscope and used to remove a sample of tissue for examination (biopsy) in a laboratory. A local anesthetic is used to reduce sensation in the esophagus during this procedure.
- Imaging Tests: Imaging tests such as chest x-rays, computerized tomography (CT scan), ultrasound, bone scan and positron emission tomography (PET) scan may be used to detect metastatic stomach cancer.
Stomach cancer may be treated with surgert, radiation therapy, or chemotherapy. Often, a combination of these treatments is used. It can be difficult to cure stomach cancer because it is often not detected until it is at an advanced stage.
1. Surgery: Surgery is the most common treatment and is the only hope of cure for stomach cancer. The surgeon removes part or all of the stomach, as well as the surrounding lymph nodes, with the basic goal of removing all cancer and a margin of normal tissue. Depending on the extent of invasion and the location of the tumor, surgery may also include removal of part of the intestine or pancreas.
- Endoscopic Mucosal Resection: Endoscopic mucosal resection may be used to treat early stomach cancer (i.e., tumor smaller than 3cm that has not invaded beyond the innermost layer of the stomach lining [submucosa]). This procedure involves removing only the tumor and surrounding tissue.
- Gastrectomy: Gastrectomy is the most common treatment for stomach cancer. In this surgery, the entire stomach (total gastectomy) or part of the stomach (partial or subtotal gastrectomy) is removed. Parts of nearby tissues or organs (e,g., spleen) may also be removed. In most cases, surrounding lymph nodes also are removed (lymph node dissection). Surgery for cancer of the upper stomach (cardia) may require removal of the stomach and part of the esophagus (called esophagogastrectomy).Following total gastrectomy, the esophagus is attached directly to the small intestine. When a large section of the stomach is removed during partial gastrectomy, the surgeon reattached the stomach to the esophagus or small intestine. The connection between these organs is called an anastomosis.
- Billroth I or Billroth II: Tumors in the lower part of the stomach may call for a Billroth I or Billroth II procedure. Billroth I (gastroduodenostomy) is formation of new opening between stomach and duodenum. In Billroth I surgery part of stomach is removed and remaining portion is anastomosed to duodenum. Billroth II (gastrojejunostomy) is anastomosis of stomach with jejunum. In Billroth II surgery duodenal stump is closed after excision of lower part of stomach.
2. Chemotherapy: Most people with stomach cancer get chemotherapy. Chemotherapy may be given before surgery – to shrink the tumor first – or after surgery, to kill any remaining cancer cells. 5-flurouracil and cisplatin are the drugs most commonly used to treat stomach cancer; other drugs (including paclitaxel, docetaxel, and irinotecan) and new combinations of conventional drugs are currently under investigation. Some are given intravenously , while others are given intraperitoneally.
3. Radiation Therapy: Radiation therapy is most commonly used in combination with chemotherapy for the treatment of gastric cancer. Patients with stomach cancer usually receive external-beam radiation therapy, which is radiation given from a machine outside the body. Radiation therapy may be used before surgery to shrink the size of the tumor or after surgery to destroy any remaining cancer cells. In some cases, radiation is administered during surgery for stomach cancer (called intraoperative radiotherapy). Radiation therapy may be used to relieve pain or blockage by shrinking the tumor for palliation of incurable disease.
Advanced Stomach Cancer : Advanced stomach cancer has spread to other areas of the body and is generally treated the same way as earlier stages of the disease, with surgery, chemotherapy, or radiation therapy. Doctors may also use surgery to relieve symptoms and prevent intestinal or stomach blockages. Chemotherapy or radiation therapy can also help relieve symptoms.
Stomach cancer cannot be prevented in all cases. With most cancers, prevention involves moderating the lifestyle and environmental exposure factors that seem to be associated with it. In the case of gastric cancer, this may be difficult, since all the causes are not well understood.
Dietary risk factors can be managed. Individuals, especially those in risk groups, should eat an adequate amount of fruits, vegetables and whole grains.
In addition, high-fat foods and animal proteins should only be consumed moderately. Most importantly, individual should minimize their intake of dried, salty foods.