Colon cancer. Barium enema X-ray of the abdomen of a colon cancer patient. The barium (bright areas) has filled this part of the colon, revealing the severe narrowing (centre) caused by the cancer. A symptom of colon cancer is bowel obstruction. The lumbar (lower) spine (vertical) is also seen. The colon (or large intestine) passes around the abdomen, forming one of the final parts of the digestive tract. Colon cancer is one of the most common cancers in North America and Western Europe. It is thought to be connected to a high fat and low fibre diet. Treatment depends upon the extent of the cancer. Barium, opaque to X-rays, is given as an enema to image the colon and rectum.