Who Should Consider Testing for Tamoxifen Response?
The CYP2D6 gene test for tamoxifen response can be considered for postmenopausal women with hormone-positive breast cancer who are taking or considering taking tamoxifen to prevent a recurrence. This use of tamoxifen is also called "adjuvant therapy." Knowing your genetic status, you can work with your doctor to decide whether tamoxifen or another effective treatment (aromatase inhibitors) are the best fit for you.
Until more research is done, tamoxifen response testing may not be right for:
- Women who are pre- or perimenopausal. This is because there are no hormonal treatments that are equally as effective as tamoxifen for these women. Tamoxifen is considered "standard of care," regardless of CYP2D6 status.
- Women with hormone-negative cancers. Tamoxifen is only recommended as a treatment for hormone positive cancers.
- High-risk women who have not had breast cancer. There has not been enough research done about this situation to know whether CYP2D6 testing would be useful.
FDA Recommends Relabeling Tamoxifen
On October 18, 2006 an FDA panel unanimously agreed that the CYP2D6 genes are a predictor of how well tamoxifen works. They recommended relabeling tamoxifen to say that CYP2D6 poor metabolizers who take tamoxifen have a higher risk for breast cancer recurrence, and that testing is available. However, these changes were never implemented.
