Do not worry so much. Answer these questions first...
1. How many times you found blood in the feces[大便]?
2. What color of the blood? Black/Green/Red?
3. What is the consistency of the feces? Hard/Form/Loose/Watery?
4. How many times you go to toilet [大便] per week?
If 腸癌, the answer should be....
1. Many times.
2. Black in color, sometimes you cannot find blood.
3. Most likely Hard.
4. Rare go to 大便 per week. In normal case, you should go to 大便 everyday or twice in three days.
If your answer all fit above I mention, you should go to see a doctor. They will do some examination for you.