I agree with Cheryl. Nobody is EVER promised that chemo will take away every last cancer cell. I also had chemo before surgery. However, I did not get entirely clean margins even after they went in the second time 3 weeks after the first time. I did radiation and Herceptin also, and I have been NED (no evidence of disease) for 5 years now. I think the bottom line is that if you trust your onc, then be at peace with having followed his/her advice. Hope that helps.
Hugs & prayers,