- Constipation: Partial blockages can slow bowel movements.
- Diarrhea: Liquids may pass around an obstruction, causing loose stools.
- Alternating constipation and diarrhea: This pattern can signal a more serious issue.
- Visible blood in stool (hematochezia): Can appear bright red or darker, depending on location.
- Worsening tenesmus: Increased inflammation intensifies the sensation of incomplete emptying.
- Bloating and cramping: Gas builds up when it can’t pass easily.
- Signs of iron-deficiency anemia: Nearly half of colon cancer patients experience this.
As tumors grow, they can lead to scar tissue and narrowing of the bowel, sometimes causing partial or complete blockages. Even if you don’t always see blood, internal bleeding may still be happening.
Stool Changes in Advanced Colon Cancer
In stage four, the cancer has typically spread to other organs. Symptoms become more pronounced, especially if there is obstruction or significant bleeding. Tumors on the right side of the colon may cause stools to appear dark and tarry (melena), due to blood being digested as it travels through the intestines.