Reprogram Cancer?

I woke up this morning and it just popped into my head, what if cancer cells could be given a function so that they are not just multiplying cell that keep multiplying.
I dont know if it is even possible to give blank cells, like cancer cells, a function but with all this DNA code i would of thought that they could be close to it.
So if they could give it some sort of function for example;
with brain tumours they could copy the code of a part of the brain cells then somehow add it to these blank cancer cells so that the tumour would act as that part of the brain and would stop multiplying maybe they can even give it the code to make it shrink so not too much pressure is caused.
Sounds like a longshot but what do you think?

Cancer could very well be the fountain of youth.

It's one of only two kinds of cells (that I know about) that can continue to grow and divide well past the limits of other cells.

Cancer is life, unbound, no? If we ever found a way to direct and control the growth of the cancerous cells, we could have a self-repairing system that continues to function for decades or even centuries longer than the one nature gifted us with.

It's a pretty cool thought.

Info on the Hayflick limit:

en.wikipedia.org...