Read this if you are HER2+ on tamoxifen

This poster presented at the San Antonio Breast Cancer Symposium further confirms the importance of CYP2D6 testing for HER2+ cancer. If you taking tamoxifen and have not had this test, ask your doctor again! http://www.posters2view.com/sabcs09/viewp.php?nu=2006

Conclusions

- Endoxifen, but not Tamoxifen, potently inhibits the estrogen stimulated growth of HER2 negative and HER2+ breast cancer cell lines that co-express ER. (10% of patients are CYP2D6 poor metabolizers and cannot convert tamoxifen to endoxifen. Another 35% have lower CYP2D6 activity and need to be very careful not to take other medications or herbals that can interfere with the conversion)

- Consistent with prior published data, we demonstrate that Tam may activate tumor growth in ER+/HER2+ cells.

http://www.tamoxitest.com/get_involved.html