[Sandy in Silicon Valley]

Dear gdpawel,

I do understand the importance of pre-testing for the likelihood of targeted therapies, like Herceptin and Tykerb, to be effective against one's bc cancer cells.

However, are the extant pathology dx tests accurate? When/if a cancerous mass contains more than one type of bc cell (my understanding is that this is, or will be, the case in most bc detectable masses before/during/after treatment), how do such tests determine which of the bc cells will die, and which will survive and go on to reproduce, in response to a particular targeted treatment?

For example, I have a "spot" in the right caudate of my brain, adjacent to the basal ganglia. This "spot" (then .5cm) was irradiated with CyberKnife in July 2005. It was undetectable in the following 3 brain MRIs. However, in Oct. 06, the "spot" showed up again, and has seemingly increased in size approximately .2cm unidirectionally, with each subsequent brain scan since then.

It could be progressive radiation necrosis (the neuro- oncologist I consulted believes so), it could be regrowing cancer cells (each possibility due to opposite scenarios - too much SRS radiation in 2005, or too little). It is too deep to biopsy.

I am on Tykerb and Herceptin currently - w/o concommitent chemo. According to my oncologist, Tykerb has only shown about 28% effectiveness against extant brain mets or growth of new lesions, in HER2-neu (with hx of brain mets) patients taking it.

Due to unpleasant side effects, I would like to stop taking Tykerb, if I knew it wasn't effective vs. my brain mets, since the Herceptin appears to be still effective other than past the BBB.

How would my bcmets be tested to predict if Tykerb was or wasn't likely to be effective in lengthening the time-to-recurrence and/or survival for me?

It's my understanding that more and more longterm radiation necrosis, some of it serious-to-fatal, is showing up in bcmets patients with hx of irradiated (WBR or SRS) brain mets. How would the targeted therapies affect such side effects, if at all?

Your knowledge is extensive, and it seems like you might have been a biochemist, working with (or studying about) cancer cells in vitro. From what I've read and heard, in vitro, and even in vivo, studies only very rarely (<10%) turn out to have relevance for human subjects, due to a number of factors.

So, what IS a "smart" pill, and how would one know that it is "smart" about one's own bc pathology?

Thanks,
Sandy in Silicon Valley