Diagnosis of stomach cancer involves taking a medical history and performing a physical examination and laboratory tests. A tumor or mass may indicate advanced disease. Tests may include fecal occult blood test, complete blood count (CBC), upper GI series (also called barium swallow), gastroscopy, and imaging tests. A doctor will decide what tests are right for the individual.

Fecal occult blood test: A fecal occult blood test is used to detect microscopic blood in the stool, which may indicate stomach or other gastrointestinal (GI) cancers, such as colorectal cancer.

Complete blood count: A complete blood count (CBC) is a simple blood test used to measure the concentration of white blood cells, red blood cells, and platelets.

Upper GI series: In an upper GI series, or barium swallow, the individual drinks a thick, chalky liquid (barium) that coats the esophagus and stomach and makes it easier to detect abnormal areas on X-rays. 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. After the test, the individual can eat normally and resume usual activities, although extra water consumption will be necessary to help flush the barium from the system. The most common complication of the procedure is temporary constipation.

Upper endoscopy: In an upper endoscopy, the doctor inserts a thin tube that contains a light and camera (called a gastroscope) through the mouth and esophagus and into the stomach. The gastroscope allows the doctor 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. Upper endoscopy takes about 20-30 minutes, although individuals are not sent home until the medication wears off, which is usually one to two hours later. Complications of the procedure rarely occur and include bleeding and perforation of the stomach lining. The most common complication is a slight sore throat from swallowing the endoscope.

Imaging tests: Imaging tests such as computerized tomography (CT scan), ultrasound, magnetic resonance imaging (MRI), and positron emission tomography (PET) scan may be used to detect metastatic stomach cancer. Once a diagnosis of stomach cancer is made, the disease is staged.

Staging :

Staging is a method of judging the progress of the cancer in an individual. Once doctors know how severe the progression of the cancer is, the best course of treatment can be followed. The staging process involves a doctor examining the tumor and the extent to which it has spread to other parts of the body. There are a number of levels of severity in staging stomach cancer. These range from 0 to 4, with 4 being the most severe stage.

Stage 0: In stage 0, the cancer has just begun to affect the inner lining of the stomach. The survival rate for those with stage 0 stomach cancer is greater than 90%.

Stage 1: In stage 1, the cancer has begun to penetrate toward the outer layer of stomach. Nearby lymph nodes may be involved. There is a 50-80% survival rate with those diagnosed with stage 1 stomach cancer.

Stage 2: In stage 2, the cancer has progressed further through tissue layers of stomach and more distant lymph nodes may be involved. There is a 30-40% survival rate with those diagnosed with stage 2 stomach cancer.

Stage 3: Stage 3 cancer has penetrated all tissue layers of stomach and distant lymph nodes may be involved. There is a 10-20% survival rate with those diagnosed with stage 3 stomach cancer.

Stage 4: Stage 4 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. There is less than a 5% survival rate with those diagnosed with stage 4 stomach cancer.

Early stomach cancer usually does not cause symptoms. Symptoms usually indicate advanced disease and include abdominal discomfort or pain, blood in stool, bloating (especially after eating), diarrhea or constipation, fatigue, gastrointestinal bleeding, indigestion or heartburn, loss of appetite, nausea and vomiting, and weight loss.

Pain: Large stomach tumors may press on surrounding nerves, leading to back or abdominal pain that can sometimes be severe.

Metastasis: Metastasis (the spreading of cancer) is the most serious complication of stomach cancer. The stomach is surrounded by a number of vital organs, including the pancreas, spleen, liver, lungs, and intestine.

Healthy cells grow and divide in an orderly way. This process is controlled by DNA, the genetic material that contains the instructions for every chemical process in the body. When DNA is damaged, these genes may not function properly, causing cells to grow out of control and eventually form a tumor - a mass of malignant cells.

Age: Most individuals with stomach cancer develop it at age 72 or older.

Sex: Men are more likely than women to develop stomach cancer.

Race: Stomach cancer is more common in Asian, Pacific Islander, Hispanic, and African Americans than in non-Hispanic, Caucasian Americans.

Diet: Studies suggest that people who eat a diet high in smoked, salted, or pickled foods may be at an increased risk for stomach cancer. Nitrates and nitrites are nitrogen-based chemicals that are added to certain foods, especially cured meats such as ham, bacon, hot dogs, and deli meats. Both nitrates and nitrites combine with other nitrogen-containing substances in the stomach to form N-nitroso compounds, which are carcinogens (cancer-causing agents) that are known to cause stomach cancer. Countries where consumption of salted meat and fish and pickled vegetables is high (such as Japan and Korea) tend to have correspondingly high rates of stomach cancer. Eating a diet high in red meat, especially when the meat is barbecued or well-done, also has been linked to stomach cancer. Eating fresh fruits and vegetables may help protect against this disease.

Helicobacter pylori infection: Helicobacter pylori, or H. pylori, is a type of bacteria that commonly lives in the stomach without causing harm. H. pylori infection increases the risk of stomach inflammation and stomach ulcers. It also increases the risk of stomach cancer, but only a small number of infected people develop stomach cancer.

Smoking: Individuals who smoke are more likely to develop stomach cancer than people who do not smoke. Smoking particularly increases the risk for stomach cancers by causing irritation of the upper portion of the stomach closest to the esophagus. The rate of stomach cancer is about doubled in smokers.

Other health conditions: Conditions that cause inflammation or other problems in the stomach may increase the risk of stomach cancer. These include stomach surgery and chronic gastritis (long-term inflammation of the stomach lining).