Genes Affect Breast-Cancer Drug Success

Women with certain gene differences may be less likely to benefit from a breast cancer drug, a study finds. The genes affect the action of an enzyme called CYP2D6. This enzyme converts the drug tamoxifen into a form that combats breast cancer. But the process doesn’t work well in women who have variations in some genes. Researchers used records of 1,325 women with breast cancer who had received gene tests. All of the women took tamoxifen. In the next nine years, cancer was much more likely to come back in women whose genes kept the body from making good use of the drug. Cancer returned in 29% of these women. This compares with 14.9% of women whose bodies used tamoxifen well. The study was in the Journal of the American Medical Association. HealthDay News wrote about it October 6.