Often, I learn from participating in an ACOR.org, listserv, on the kind of cancer that I had (colon cancer) and this response from our moderator -genius- Kate Murphy, was good, that I asked her if I could share the response.

"It is a puzzle to researchers too.

Not everyone responds to any one of the drugs that are given for colorectal
cancer -- not even one of the them.

Tumors are very different, and a lot of research is going into why some
tumors respond and some don't.  More research is being done into why cancers
become resistant to particular chemos -- and they all eventually do.

We have made a very small step in understanding that people who have certain
KRAS mutations don't benefit from Erbitux or Vectibix.  This is farther than
many cancer types have come.

But we have the scientific power now to look at many different changes in
tumor genes and proteins and we are doing it faster and cheaper.  It isn't
one mutation at a time now, but several thousand.  Best of all, we have the
computer power to do it.

Basically, signals get sent along pathways in the cell toward the center or
nucleus with messages that tell cells to divide, die, or stand still.  We
are learning to block those signals at key points and keep the ones that say
"divide" from getting to the target or clear the way for the ones that are
saying "die."  Of course, if you have ever been stuck in traffic, you may
have found a way to turn a corner, find a different route and miss the
stoplight on the next corner.

Complex to do  . . . but we are doing it.

Meanwhile, patients basically try drugs one after the other . . . and see if
they work for them and for how long.

I am confident that this will change in the future, maybe sooner than we
think.

I also believe we are going to find more drugs that block bad signals and
cooperate with other drugs to block other pathways that let signals sneak
through."

Kate