What Are the Signs of Colon Cancer? In its early stages, colon cancer often doesn’t cause noticeable symptoms. However, some signs can raise concern, including: Blood in your stool. Changes in bowel habits, such as constipation or diarrhea lasting for weeks. Fatigue with unexplained weight loss. Rectal bleeding. If you notice any of these symptoms, it’s important to talk with your healthcare provider. Screening Recommendations Screening for colon cancer is recommended startin