In its early stage, colorectal cancer usually produces no symptoms. The most likely warning signs include: Understanding Colorectal Cance Find out more about colorectal cancer

Basics

Symptoms

Diagnosis and Treatment

Prevention

Changes in bowel movements, including persistent constipation or diarrhea, a feeling of not being able to empty the bowel completely, an urgency to move the bowels, rectal cramping, or rectal bleeding

Dark patches of blood in or on stool; or long, thin, "pencil stools"

Abdominal discomfort or bloating

Unexplained fatigue, loss of appetite, and/or weight loss

Pelvic pain, which occurs at later stages of the disease