Colon cancer is a common type of malignancy in which cancerous cells form in the tissues of the large intestine, more commonly known as the colon. More than 95 percent of colon cancers are adenocarcinomas, originating in the glandular epithelium that produces and secretes mucous and other thick fluids, according to CancerHelp UK. In most cases, colon cancer begins as a noncancerous polyp. Certain types of polyps, particularly adenomatous polyps, are most likely to become cancerous over time, notes MayoClinic.com.
Bleeding from the Tumor
Fresh blood in the stools can be from an affected colon, which is an obvious sign of colon cancer. Bleeding from the tumor is, however, frequently confused with bleeding piles and anal fissures. Blood in the stools may only be visible upon wiping the anus, or blood may be encompassed within the stool and therefore not be clearly evident. Sometimes, the stools may change to very dark and black in color due to large amounts of bleeding.
Change in Bowel Habits
In colon cancer, some people have bouts of diarrhea, and some have bouts of constipation. Colon cancer can compress, squeeze or narrow the large intestine and block the passage of the stool, leading to constipation. Bowel obstruction doesn't occur until late in the course of cancer. The stools become hard and dry, and difficult or painful to pass. Diarrhea means bowel movements occur more frequently than usual, and the stools are loose, mushy and watery.
Pain Symptoms
Symptoms may worsen as the colon cancer grows beyond the inside of the colon. People often feel very weak and tired all the time, and lose weight with no reason. Obstruction of the colon causes acute abdominal pain and other complications like vomiting, notes Patient UK. In some cases, the cancer creates a hole in the colon that allows the feces to leak into the abdominal cavity, causing severe pain.
