Stomach cancer or gastric cancer, refers to cancer developing in any part of the stomach. These cancers are classified according to the type of tissue they originate in. The most common type of stomach cancer is adenocarcinoma, which starts in the glandular tissue of the stomach and accounts for 90-95% of all stomach cancers. Other forms of stomach cancer include lymphomas, which involve the lymphatic system and sarcomas, which involve the connective tissue (such as muscle, fat or blood vessels). Stomach cancer is often curable, if found and treated in an early stage.
In the early stages of stomach cancer, the symptoms are not very clear. But in the later stages the following symptoms manifest themselves:
- Indigestion and stomach discomfort
- A bloated feeling after eating
- Mild nausea
- Loss of appetite
These symptoms are similar to those caused by a peptic ulcer. If you are experiencing any of these symptoms, you should see your health care provider so that a proper diagnosis can be made and timely treatment given. A stomach cancer can grow very large before it causes other symptoms.
In more advanced cancer, you may have:
- Discomfort in the upper or middle part of the abdomen.
- Blood in the stool (which appears as black, tarry stools).
- Vomiting or vomiting blood.
- Weight loss.
- Pain or bloating in the stomach after eating.
- Weakness or fatigue associated with mild anaemia (a deficiency in red blood cells).
The exact cause of stomach cancer is unknown, but a number of factors can increase the risk and causes of the disease, including:
- Gender: According to studies, men have more than double the risk of getting stomach cancer in comparison to their female counterpart.
- Race: The occurrence of stomach cancer is on the higher side among African-American or Asian.
- Genetics: Genetic abnormalities and some inherited cancer syndromes may increase an individual’s risk towards developing stomach cancer.
- Blood type: Individuals with blood group A may be at increased risk.
- Advanced age: Stomach cancer occurs more often around ages 70 and 74 in men and women, respectively.
- Family history of gastric cancer can double or triple the risk of stomach cancer.
- Lifestyle factors such as smoking, drinking alcohol and eating a diet devoid of fruits and vegetables or high in salted, smoked or nitrate-preserved foods may increase risk.
- Helicobacter pylori (H. pylori) infection of the stomach: H. pylori is a bacterium that infects the lining of the stomach and causes chronic inflammation and ulcers.
- Certain health conditions, including chronic gastritis, pernicious anaemia, gastric polyps, intestinal metaplasia and prior stomach surgery.
- Work-related exposure due to coal mining, nickel refining and rubber and timber processing and asbestos exposure.
If anyone of the following symptoms occurs, such as indigestion, weight loss, nausea and loss of appetite, screening tests may be recommended. These tests may include:
- Upper GI series: These are X-rays of the oesophagus, stomach and first part of the intestine taken after you drink a barium solution. The barium outlines the stomach on the X-ray, which helps the doctor, using special imaging equipment, to find tumours or other abnormal areas.
- Gastroscopy and biopsy: This test examines the oesophagus and stomach using a thin, lighted tube called a gastroscope, which is passed through the mouth to the stomach. Through the gastroscope, the doctor can look directly at the inside of the stomach. If an abnormal area is found, the doctor will remove some tissue (biopsy) to be examined under a microscope. A biopsy is the only sure way to diagnose cancer. Gastroscopy and biopsy are the best methods of identifying stomach cancer.
Once stomach cancer is diagnosed, more tests may be performed to determine whether the cancer has spread. These tests may include CT scans, PET scans, bone scans, laparoscopy and endoscopic ultrasound.
Other tests undertaken:
- Physical exam: The doctor feels the abdomen for fluid, swelling or other changes. The doctor will also check for swollen lymph nodes.
- Endoscopy: The doctor uses a thin, lighted tube (endoscope) to look into the stomach. He first numbs the patient’s throat with an anaesthetic spray. The tube is then passed through the mouth and oesophagus to the stomach.
- Biopsy: An endoscope has a tool for removing tissue. The doctor uses the endoscope to remove tissue from the stomach. A pathologist checks the tissue under a microscope for cancer cells. A biopsy is the only sure way to know if cancer cells are present.
Cancer of the stomach is difficult to cure unless it is found in an early stage. Unfortunately, because early stomach cancer causes few symptoms, the disease is usually advanced when the diagnosis is made. Treatment for stomach cancer may include surgery, chemotherapy and/or radiation therapy. New treatment approaches such as biological therapy and improved ways of using current methods are being studied in clinical trials.
Surgery is the most common treatment. The surgeon removes part or all of the stomach, as well as the surrounding lymph nodes, with the basic goal of removing all of the cancer tissue and a margin of normal tissue. Depending on the extent of invasion and the location of the tumour, surgery may also include removal of part of the intestine or pancreas. Tumours in the lower part of the stomach may call for a Billroth I or Billroth II procedure.
Endoscopic Mucosal Resection (EMR) is a treatment for early gastric cancer (tumour only involves the mucosa) that has been pioneered in Japan, but is also available in the United States at some centres. In this procedure, the tumour, together with the inner lining of stomach (mucosa), is removed from the wall of the stomach using an electrical wire loop through the endoscope. The advantage is that it is a much smaller operation than removing the stomach. Endoscopic Submucosal Dissection (ESD) is a similar technique pioneered in Japan, used to resect a large area of mucosa in one piece. If the pathologic examination of the resected specimen shows incomplete resection or deep invasion by tumour, the patient would need a formal stomach resection.
Surgical interventions are currently curative in less than 40% of all cases, and in cases of metastasis may only be palliative.
The use of chemotherapy to treat stomach cancer has no firmly established standard of care. Unfortunately, stomach cancer has not been particularly sensitive to these drugs and chemotherapy, if used, palliatively reduces the size of the tumour, relieves symptoms of the disease and increases survival time.
Radiation therapy is the use of high-energy rays to damage cancer cells and stop them from growing. When used, it is generally in combination with surgery and chemotherapy, or used only with chemotherapy in cases where the individual is unable to undergo surgery. Radiation therapy may be used to relieve pain or blockage by shrinking the tumour for palliation of incurable disease.