The symptoms of colon cancer may include:

  • Blood in the stools, turning feces a bright or dark red.
  • Changes in normal bowel habits, such as diarrhea or constipation, when such changes happen with no apparent reason and last for more than three weeks.
  • Unexplained weight loss.
  • Abdominal pain.
  • Feeling of not having emptied your bowels fully after having a movement.
  • Unexplained fatigue.

Sometimes, cancer can cause a blockage (obstruction) in the intestine, provoking constipation and bloating, vomiting, and abdominal pain.