There has been a question exactly like this a few months ago. I'll just quote my answer to that post, if you don't mind.
"Oh my! There are a lot of chemotherapeutic agents and each agent is a combination of different elements. For example, Chlorambucil, a chemotherapy drug that is given as a treatment for Hodgkin lymphoma, is C14H19Cl2NO2 so it uses the elements Carbon, Hydrogen, Chlorine, Nitrogen and Oxygen. If you really must get all the elements in all chemotherapeutic drugs, you can go to
Individual chemotherapy drugs : Cancerbackup. The individual chemotherapy agents are listed at the left side of the screen. Search each drug and usually they mention the chemical formula in wikipedia."