Cancer cells and between the body's normal immune system, fighting never stopped. Fortunately, the body's normal immune system has won the majority of the fighting.
However, everything changes, and in some particular time, cancer cells gain an advantage, while the body's normal immune system at a disadvantage,the fighting result may be that we do not want to see.

Even if the occasional cancer cells to overcome the body's normal immune system, we still should not  panic. What we need to do is quickly reversed the situation, re-win the dominant position, this is very important, very urgent!
For us normal people, we need to do is to maintain its own immune system to normal state, this is actually not hard to achieve.
We need to abandon some bad habits, such as smoking, alcohol, excessive tiredness, depression, rage ...

As long as we did, we won a wonderful life.
Perhaps, human beings can never be clear of cancer, but we can win cancer.