[Lani]

there has been a clinical trial showing that adding herceptin to letrozole(femara) improves disease free survival in those with metastatic breast cancer better than letrozole alone. The opposite has never been done.

Theoretically there is cross talk between the ER pathway and the her2 pathway and both should theoretically be blocked to avoid "escape" via the unblocked pathway. Dr. Slamon has stated at several conferences that he believes the best antihormonal treatment for those who are her2+ and treated with herceptin is faslodex, as it works in another way (it causes the estrogen receptors to fall off every cell irreversibly). Now that may be scary in those cells in one's body with estrogen receptors which do not often multiply and thus are unlikely to be replaced with new cells with estrogen receptors. These include the brain. Originally it was thought that faslodex may not cross the blood brain barrier, but a recent article supported that it does.

The absolute answer is not available and that may be because ER+her2+ breast cancer represents about 10% of all breast cancer and because a recent article I posted showed that delay from time of taking the biopsy to placing the specimen formalin may alter the ER, PR and her2 results. So a lot of "conclusions" and even Adjuvant online and results of many clinical trials and stats presented to patients may not be accurate. Lots to think about, but the answer is....we don't know yet.