ROCHESTER, Minn. — Clinical recommendations discouraging the use of CYP2D6 gene testing to guide tamoxifen therapy in breast cancer patients are based on studies with flawed methodology and should be reconsidered, according to the results of a Mayo Clinic study published in the Journal of the National Cancer Institute.
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For years, controversy has surrounded the CYP2D6 gene test for breast cancer. Women with certain inherited genetic deficiencies in the CYP2D6 gene metabolize tamoxifen less efficiently, and thus have lower levels of tamoxifen’s active cancer-fighting metabolite endoxifen. Numerous studies have shown that these women gain less benefit from tamoxifen therapy and have higher rates of recurrence.
Joe Dangor, Mayo Clinic Public Affairs, 507-284-5005, email@example.com.