How will they decide what type of chemotherapy to give me?

Your specialist will choose the best type of treatment to give you.
This depends on what type of cancer you have, how far it has spread
and your general health. Everybody is different and everyone has their
treatment especially designed for them. This means somebody else's
reaction may be completely different to yours.
Chemotherapy has been used for many years now.
There are new and better treatments being discovered all the time.
So your doctors will have a good idea of the best treatment for you.
During your treatment your doctors will keep a close eye on you.
You will probably have blood tests, x-rays and scans to see how
you are going. If necessary your doctors will change your
drugs or how they give them to you. Sometimes they will stop the
treatment early or continue it for longer than planned.
It all depends on how your body and the cancer are responding to the treatment.