How long does chemotherapy stay in your system after treatment? 2 answers | Last updated: May 16, 2011 Q A fellow caregiver asked... How long does chemotherapy stay in your system after treatment? Answers audrey-1 A 5% helpful audrey-1 answered... i dont have an answer thats why i am asking. More Answers cherrykoke cherrykoke answered... Ifound a site that said approx 2yrs after treatment stop . depends on what drug would like a direct answer myself ! Recommended for You Neuropathy and Chemotherapy: What You Can Do How do I get the Doctor to be More Responsive? How do we decide when to stop chemotherapy that's not working? 12 Ways to Cope With "Chemo Brain"