Bowel cancer is a common disease. It can range from a small nodule found on colonoscopy to metastatic disease in which the cancer has spread to multiple organs throughout the body. Treatment depends on how far the cancer has progressed, in other words the stage of the cancer. Since bowel cancer is so common and the prognosis, or outcome, depends on the stage at which it is found, guidelines have been established for screening. Therefore, some cancers are found by screening, and others are found because of symptoms.
Blood in the Stool
Blood in the stool is generally one of two types. Hematochezia refers to visible blood in the stool. It is more common with bowel cancers in and near the rectum, and brisker bleeding. Melena refers to black, sticky tar like stool. It is more common with bowel cancers elsewhere in the gastrointestinal tract. A 2008 article by Dr. Ford et al. in the medical journal "Gut" noted a prevalence of rectal bleeding of 49 percent.
Iron Deficiency Anemia
Iron deficiency anemia refers to low iron and red blood cell counts in the blood. Symptoms may include fatigue and pallor, which is a lightening of the skin color. Bowel cancers can cause anemia from blood loss into the GI tract. The 2008 article in "Gut" placed the frequency of iron deficiency anemia at about 10 to 15 percent.
Abdominal Pain
Abdominal pain has several potential causes associated with bowel cancer. A tumor can grow and obstruct the GI tract, leading to difficultly in passing products of digestion through the GI tract and pain with distension of the tract. The cancer can also perforate the intestine, spilling intestinal contents into the abdominal cavity and causing inflammation and infection there. Bowel cancers may also cause pain by invading the pelvic or abdominal nerves.
Change in Bowel Habits
The article in "Gut" noted that a change in bowel habits occurred in about 30 percent of people. The change in bowel habits, such as diarrhea, constipation or a change in the size of stool may occur if the cancer encircles the GI tract making it more narrow. This can also cause abdominal pain, distension, nausea and vomiting.
References
- "Harrison's Principles of Internal Medicine"; Anthony Fauci et al; 17th Ed 2008
- "Gut"; Diagnostic utility of alarm features for colorectal cancer: systematic review and meta-analysis; November 2008
