[Gerri]

http://theoncologist.alphamedpress.o.../full/13/6/620

Taken from the above referenced article:

Another concern regarding the use of trastuzumab has been the association of its use with the development of metastatic CNS disease. A higher incidence of progression in the CNS has been observed in several retrospective studies of patients with HER-2–positive metastatic breast cancer treated with trastuzumab [43–45]. Our analysis demonstrated a higher incidence of CNS metastasis as the first recurrence event among patients treated with trastuzumab, which nonetheless was outweighed by the overall lower risk for distant recurrence (non-CNS visceral disease) and the impressive benefits in survival. The exact reasons for this phenomenon are unclear, but the etiology is probably multifactorial, involving a lower bioavailability of trastuzumab in the CNS because of poor blood–brain barrier penetration and its high effectiveness in preventing the development of non-CNS visceral disease. Although some investigators have suggested that HER-2–positive disease may preferentially involve the CNS, evidence from large retrospective datasets of nontrastuzumab-treated patients is inconclusive [46, 47].

So, do I show this to my onc to get her to order an MRI?