Cancer of the digestive system includes tumors in the esophagus, stomach, liver, pancreas, gallbladder, and colon, which might involve the rectum or anus. Each type of gastrointestinal cancer develops from cells found in the specific organ. Some forms of cancer of the digestive system fail to produce symptoms until the disease becomes advanced, but screening might identify tumors at an early stage.
Pancreatic cancer is considered difficult to diagnose and treat because this type of cancer of the digestive system rarely develops early signs. Two kinds of cells in the pancreas might become cancerous: endocrine cells or exocrine cells. Endocrine cells produce hormones the body uses for many different functions. Also called islet cells, tumors in these cells rarely become cancerous.
Exocrine cells make enzymes needed to digest food. They exist in sacs where 95 percent of all pancreatic cancer begins. Malignant tumors may cause stomach or back pain, diarrhea, or heartburn as the cancer spreads within the pancreas or to nearby organs. In some patients, the skin and whites of the eyes take on a yellowish tint. The prognosis for cancer of the digestive system involving the pancreas depends on the stage of the disease, whether it has spread, and the type of abnormal cells.
Primary or secondary liver cancer might develop within the liver or elsewhere before spreading to this organ. The liver sits inside the rib cage and serves as a filter for harmful substances. It sends toxic material to the urine and feces for excretion and produces bile to digest food. Tumors in the liver typically progress to an advanced stage rapidly and occur more often in people with cirrhosis or hepatitis.
Stomach cancer usually starts in cells in the inner lining of the stomach before spreading to other layers. Acids in the stomach break down carbohydrates, fats, protein, vitamins, and minerals for use. Advanced stomach cancer might make swallowing difficult, produce pain, or show up as bloody stools. Indigestion, nausea, and loss of appetite represent other symptoms of the disease. Risks of stomach cancer increase with age, poor diet, and other stomach conditions, such as bacterial infection, inflammation, and ulcers.
Colon cancer might develop in the large or small intestines, and represents the most common form of cancer of the digestive system. It might be cured if caught early by surgically removing tumors or a section of the colon where cancer cells exist. Any change in bowel habits, such as constipation, diarrhea, smaller stools, or bloody feces, might indicate colon cancer. People over the age of 50 and patients with a family history of colon cancer face higher risks of the disease.