Racial differences in drug metabolism: an explanation for higher breast cancer mortality in blacks?

The risk of dying from breast cancer differs between racial groups, and the reason for this racial difference is unknown. In this paper, we hypothesize that racial differences in breast cancer mortality may be due to racial differences in the metabolism of drugs used to treat women with breast cancer. Racial differences in the metabolism and effectiveness of other commonly used drugs have been described, and these differences are thought to result from genetic differences in the cytochrome P450 enzyme system. Tamoxifen, widely used for breast cancer treatment, is metabolized by the cytochrome P450 system. Preliminary evidence from human studies suggests that this agent is less effective in non-whites than whites; however, more definitive studies are needed. A better understanding of racial differences in cytochrome P450 drug metabolism and subsequent effectiveness will lead to better breast cancer treatment for all women.