Johana,
Thanks for clarifying this important fact that you had WBR.Based on the post by Lani (
http://www.her2support.org/vbulletin...ad.php?t=26300) which shows that Herceptin can in some circumstances cross the blood brain barrier, the likelyhood is increasing  that Herceptin is responsible for your brain mets disappearing due to the possible action of WBR in weakening the barrier.
If that is the case you may have made a contribution toward proving the feasability of a new way for Herceptin to control brain mets.
In any case congratulations for your successfull outcome!