Cancer can develop almost anywhere in the digestive tract. The digestive tract (alimentary canal) starts at the mouth and continues for nearly 30 feet (approximately 9 meters) before it reaches the anus, where waste products are eliminated. It is a complex system of organs that help the body digest food and eliminate waste.  If cancers that impact the digestive tract are detected and treated in their earliest stages, they are highly curable in most cases. Some cancers commonly associated with digestive problems include:

• Oral and throat cancer. The early signs of oral and throat cancer will develop mainly in the soft tissues of the mouth. Most oral cancers develop on the tongue, on the floor of the mouth, inside the cheek, on the gums or on the roof of the mouth. Symptoms of these cancers can include:
  
  
• • Sores in the mouth that do not heal or increase in size
    
    
  • Lumps or colored patches inside the mouth
    
    
  • Thickening of the cheek or other mouth tissues
    
    
  • Chewing or swallowing difficulties (dysphagia)
    
    
  • Numbness or difficulties moving the tongue
    
    
  • Pain or swelling in the jaw
    
    
  • Persistent sore throat or  the feeling of something caught in the throat
    

• Esophageal cancer. Some of the signs and symptoms of esophageal cancer include dysphagia (difficulty swallowing), severe and unintentional weight loss, pain or burning of the throat as food travels through the esophagus.  In addition, an individual may experience pain in the chest or between the shoulder blades, hoarseness, chronic cough or coughing up blood. Small tumors rarely cause symptoms until the disease progresses.
  
  
• Stomach (gastric) cancer. At its earliest stages, microscopic internal bleeding is a possible sign of stomach cancer. This sign can be detected only by looking for trace amounts of blood in the stool using certain tests. As the disease progresses, other signs and symptoms may include abdominal discomfort that is not relieved with antacids and may be aggravated by eating. Patients may also exhibit bloating of the stomach or vomiting after meals, vomiting of blood or stools that are black or tarry.
  
  
• Gallbladder cancer. Some of the signs and symptoms of gallbladder cancer include abdominal pain, nausea, vomiting, loss of appetite and weight loss.
  
  
• Liver cancer. There are very few signs or symptoms of liver cancer in its early stages. As the disease progresses, it may cause noticeable symptoms such as loss of appetite or weight, abdominal pain, nausea and vomiting. Patients may also exhibit an enlarged liver, abdominal swelling or decreased liver function as detected by tests.
  
  
• Pancreatic cancer. There are very few signs or symptoms of pancreatic cancer in its early stages, which often leads to a late diagnosis when the disease is far less treatable. For this reason, it is one of the deadliest types of cancer. As the disease progresses, pancreatic cancer can cause loss of appetite, significant weight loss, nausea and vomiting. Digestive problems are common with this cancer due to the challenges of digesting certain foods, particularly those high in fat.

  

• Bile duct cancer (cholangiocarcinoma). Some of the signs and symptoms of bile duct cancer include an enlarged gallbladder, coffee-colored urine, loss of appetite, weight loss and white or clay-colored stools.
  
  
• Colorectal cancer. Colon cancer originates in the large intestine (colon) and rectal cancer starts in the rectum. Since these two types of cancers share common features, they are sometimes combined as colorectal cancer. This type of cancer does not produce many signs or symptoms of disease in its earliest stages. When symptoms do appear, they  depend on the size and location of the tumor, as well as the stage of the cancer. Generally, symptoms of colorectal cancer include a change in bowel habits (such as diarrhea or constipation), pencil-thin stools, rectal bleeding or blood in the stool, or cramping in the lower stomach. Many patients may also have an urge to have a bowel movement when there is no need to have one, painful gas or unexplained weight loss.
  
  
• Anal cancer. The anus is located at the end of the large intestine (bowel). This opening allows stools to be passed during a bowel movement. Cancer can develop in the portion of the anus that is inside the body or the part that is outside the body. Symptoms of this type of cancer are similar to several of those found with colorectal cancer.

Approximately 50 percent of gastrointestinal carcinoid tumors (hormone-secreting tumors that develop in the lining of the gastrointestinal tract) are diagnosed as a result of symptoms, according to the American Cancer Society (ACS). The most common symptom is stomach pain, which can continue for years until the tumor is found. Carcinoid tumors can cause a wide array of symptoms, including intestinal bleeding, diarrhea and flushing of the skin.

There are several other cancers that are not related to the digestive tract but nonetheless may cause digestive problems as they progress. These include:

• Metastatic breast cancer. When breast cancer spreads (metastasizes) to other sites in the body, it can cause a variety of digestive problems. Bloating, pain and vaginal bleeding are symptoms of metastases to the ovaries, whereas abdominal pain and digestive problems may signal metastases to the liver or stomach.

• Endometrial cancer. Cancer of the lining of the uterus (womb) may produce pelvic pain, unusual bleeding, spotting and weight loss in patients.
  
  
• Ovarian cancer. Ovarian cancer is often diagnosed in its later stages because two of the major symptoms – indigestion and abdominal swelling – are common signs of many conditions other than cancer. Individuals often attribute the digestive problems to less serious conditions, leading to a late diagnosis of ovarian cancer.

Additionally, treatments for cancer can also cause digestive problems in some individuals:

• Chemotherapy. Chemotherapy is a method of treating various cancers using powerful drugs that attack cancer cells and help prevent the spread of the disease. This treatment may cause the following digestive problems:
  
  
• • Loss of appetite and weight loss
  • Nausea and vomiting
  • Diarrhea or constipation
  • Sensitivity to smell and taste
  • Difficulty with digestion
  • Mouth or lip sores
    
    
  Many of the side effects of chemotherapy may be alleviated with medications. A patient’s cancer care team can help determine the best ways to combat the digestive problems experienced from treatment.
  
  
  
• Radiation therapy. Radiation therapy uses a specific type of precise x-rays to kill or shrink cancer cells. When directed at the chest or abdomen, radiation therapy may cause swelling or inflammation of the esophagus or intestines, which, in turn, can lead to nausea, vomiting and/or diarrhea. Antacids can help, as can dietary modifications (e.g. avoiding spicy, fried or high-fiber foods). In severe cases, dehydration may be severe enough to require administration of intravenous fluids.

From time to time, most people will experience some type of digestive problem, particularly diarrhea or constipation. Many common digestive problems can be caused by conditions that require medical attention, but are less serious in nature than cancer. These may include:

• Gastrointestinal infections. These infections can be a result of exposure to viruses, bacteria or possibly intestinal parasites.
  
  
• Appendicitis. Abdominal pain, fever, loss of appetite and vomiting are all symptoms of inflammation of the appendix. In advanced cases, the appendix may need to be removed immediately to avoid rupture and serious medical complications.
  
  
• Gastritis and peptic ulcers. Strong acids produced by the stomach can sometimes irritate the stomach and duodenum (the first part of the small intestine).Left untreated, ulcers can cause damage to the digestive tract and organs.
  
  
• Inflammatory bowel disease. This chronic condition is an inflammation of the intestines.
  
  
• Celiac disease. Some people are unable to tolerate a protein called gluten, which is found in wheat, rye and barley and a wide range of processed foods. Some of the most common digestive problems associated with this condition include abdominal cramping, abdominal distention, constipation, diarrhea, excessive gas or steatorrhea (stools that are fatty and thus float instead of sinking).
  
  
• Irritable bowel syndrome (IBS). This common intestinal disorder causes abdominal cramping, bloating, constipation and diarrhea.