how do you know you are cancer free?

[Alyce]

I usually forget to ask all my questions when I see my Onc. and here is one for all of you who have continued on for more than one year of herceptin. Is there a time when you can be tested to know that you are cancer free? I wonder if you just go for your mamograms and assume that you are cancer free if nothing shows up?
How does your Onc. determine the length of time for you to continue on with herceptin when it goes beyond the year?
Also- I met a woman at my radiation appt. who is being treated again after 22 years, and while she was on chemo this time they found another cancer in her breast. Very confusing to me. So does that mean that a brand new cancer came into existence, overcoming the current chemo?
It would be nice if there was a test to actually tell you that you are cancer free. I am kind of nervous thinking that even while we are taking Femora and herceptin we might still have active cancer cells.