How do you know if Herceptin is working??

[linn65]

I am ER+, HER2+++, PR-, several lumps with the biggest being over 5 cm. The doctor deciced he wanted me to do preadjuctive (sp) chemo therapy being TCH which I just finished on November 27th...THANK GOD!!

In the beginning he did bone scan, cat san, muga scan and MRI. Then when we finished another Muga scan, MRI, mammo, and ultrasound.

When for check up yesterday and he said now we will do surgery with no reconstruction for 6 months so by body can heal from chemo because blood is thick and we do not want to get blood clots and weakened body from chem. And after surgery I will have to do radiation for 6 weeks and 9 more months of herceptin.

But my question is how do they know the herceptin is working???? My tumor has not grown so that is good but it has not shrunk. So I am thinking HER2 is in your blood stream and therefore the herceptin for the year.

Then what happens??? I just don't know how you know if it is working......