How long till tumor shrinks on Chemo?

Ellie, I've read and heard that tumors don't necessarily shrink as we might think--they can shrink in a way that makes them look like swiss cheese. That gave me some comfort, when after six rounds of chemo, I could still feel something. They'd done ultrasounds and said it was shrinking, but it was still very much there. My final pathology after surgery found no live cancer cells and only a "tumor bed." I remember thinking as I drove to surgery at zero dark thirty that what I was still feeling had to be the tumor, but it wasn't. Until that point, no one had explained to me that there is something left there, even if there are no live cells at the site. She has a ways to go, and the chemo still has plenty of time to work.