Doctors have long known that breast cancer is more deadly in black women; new research suggests why: They are more likely to suffer from treatment-resistant tumors, a major study at the University of Michigan concludes. Analysis of data from nearly 100,000 women with later-stage breast cancer shows that black patients have higher incidence of tumors that don't respond to hormone-blocking drugs that inhibit growth.
About 39% of black women in the group had drug-resistant tumors compared to 22% of white women. Black women develop breast cancer less frequently than whites but their cancers are more likely to be fatal. Previous efforts to explain the disparity have focused on inferior health care. The Michigan study presents the strongest argument yet for a biological component to the inequity.