Cancer is ever-changing. It's got you by the throat and is not about to let go. There will be times along the way that you can keep it at bay with a certain chemo or treatment, which will work for a period of time. However, because cancer is the smartest devil in the room, it will eventually find a way around your treatment and prevail.
That's why I am always harping on the critical need to fund research to create new drugs to block the spread of cancer. I have been on one of those drugs for two years.