Cecal and other right- sided colon cancers are most often called to clinical attention by the appearance of fatigue and weakness due to iron deficiency anemia. Thus, it is a clinical maxim that the underlying cause of iron deficiency anemia in an older man or postmenopausal woman is GI cancer until proven oth- erwise. Left-sided colorectal adenocarcinomas may produce occult bleeding, changes in bowel habits, or cramping and left lower quadrant discomfort.