I should note that it is often times important to review the actual clinical study relating to a medical issue rather than rely upon outside reporting of the study. This is one such case. The cancerfacts article regarding the occurrence of CNS metastates with respect to women on Herceptin is confusing. However the conclusion of the actual medical study appears sound. Accordingly I have provided a cross-link to the actual medical study abstract.

The conclusion of the study is as follows:

Metastatic breast carcinoma to the CNS is common among patients receiving trastuzumab-based therapy including patients responding to therapy outside the CNS. This may be due either to predilection for the CNS by HER-2-positive tumor cells and/or poor penetration of the CNS by trastuzumab or to improved visceral disease control leading to a longer life and onset of late tumor spread to the CNS. Efforts to characterize other risk factors for development of CNS disease optimal screening algorithms and new treatment strategies may be warranted.