CA15.3, must I change?

[michka]

Hello to all. I know CA.15.3 markers are not very reliable. However, they allowed me to detect my metastasis. They were at 25 for years and went to 28 and then 32 end 2010. I asked for a Pet/Scan and although my onc thought it was for nothing he accepted.
Since my liver resection in March these markers were always around 36 or 38. I didn't like that because I thought that if Navelbine worked the markers should go down back to 25. My liver MRI is clear so my onc is satisfied and I continue on Navelbine although I am having a hard time.
Now the CA15.3 are 44. I know it is a small increase but in my case it may be significant.
My next Pet/Scan is on September 7th.

My question: should I try switching to Tykerb/Xeloda for example to see if it impacts the markers or stick to Navelbine and wait to see if another metastasis showed up?
Other question I already asked but...should I add an anti estrogen like Faslodex? My onc does not like the idea. He thinks it could be antagonist with the chemo.

Any opinion is welcome. Michka