Cancer as a terrorist

I heard an interesting story about cancer from my friend who is a doctor. According to him, cancer is an error of cell division and each cancer cell is anarchy just like a terrorist. It has been existed since human beings were born, however, the longer our life span, the more possibility of cell division error, and the more people die of cancer. If this theory is true, cancer seems to be a kind of warning timer telling us "you have lived too long." Of course, losing our family or friends is a great grief, but should we or could we change our destiny by conquering cancer? As for me, I don't like to live for a long time over the limitation. All I want is that all my body including my brain, eyes, ears, hands, legs and so on, are fully working until the moment of my death.