Rectal cancer Also known as bowel or colorectal cancer, colon cancer is a malignant tumor of the rectum or colon. Rectal cancer affects the last part of the bowel. The cause of colon cancer is usually unknown, but risk factors include a diet high in red or processed meat and low in fiber; being overweight; lack of exercise; smoking; excessive alcohol consumption; a family history of colon cancer; and a personal medical history of certain long-standing inflammatory bowel disorders, such as ulcerative colitis or Crohn’s disease.
Rarely, colon cancer is due to the inherited disorder familial adenomatous polyposis, in which numerous polyps grow in the bowel.
Symptoms include changes in the frequency of bowel movements or in the general consistency of the feces; persistent blood in the feces; persistent lower abdominal pain, bloating, or discomfort; a sensation of incomplete emptying of the bowel after defecation; and loss of appetite. Treatment depends on the location and stage of the cancer. In most cases,
treatment involves surgery to remove the affected section of bowel, sometimes combined with chemotherapy, radiation therapy, or biological treatments (medications that shrink the tumor). Some countries have screening programs to detect the disease early.