A 57-year-old obese woman with diabetes visits her primary care physician for her annual examination. She reports an unintentional 20-lb weight loss over the past few months, without despite no changes in her diet or physical activity. She also describes experiencing pencil-thin stools, intermittent constipation, and a sensation of incomplete bowel evacuation. She also reports that there was no blood or mucus in her stool. Her medical history includes a 20 pack-year smoking history, and she has never undergone a colonoscopy. There is no family history of cancer. On physical examination, she is afebrile with a heart rate of 78 beats per minute and blood pressure of 132/74 mmHg. Her abdomen is soft, non-tender, and non-distended, with no palpable masses. Rectal examination shows no masses or visible blood. Laboratory studies reveal a hematocrit of 37% (normal range: 40–52%).