How does anticancer drugs produced through biotechnology?

I think it is a case of .. Well in very basic terms... harness and/or 'cripple or slow'
the cells which are damaged to the point of divergent to normal behavior.

Nano devices might be able to be chemically programmed to recognise the trace emissions different to genetic normalcy, perhaps performing incisory action in acceptably small area around said emissions, though that's my speculation as a complete non-biologist with no research, but as my name states, I am bored.
Also processing and basic subroutines might be possible but perhaps slow, given, I assume the lack of space for CPU power.

Sorry, I know nothing, nothing! I say!

Any time I pondered any cancer issues I hit a wall of rebound, which implied any fix, would leave a definite percentage of failure, however slight.