question: my husband is afraid he might have colon cancer. He has tenderness and a feeling of swelling  in the upper right abdomen. So far he did all the cancer blood markers, which where negative, and an accurate ultrasound, which showed kidneys, bladder, liver etc and found no anomalies whatsoever, and a fecal test, which was negative for blood.  He did not have a colonoscopy yet. He's 52, smoker, and lately has been suffering with Lichen Ruber in his torso (front and back) and head. Any clues? Thank you