The new study was presented at the American Association for Cancer Research conference in Philadelphia.
Doctors at the Duarte Institute for Cancer Research in Duarte, California, have found that black and white women have different breast cancer treatment efficacies when taking hormonal drugs.
Nearly 70 percent of all cases are treated with hormone therapy. However, black women are four times more likely to die than white women.
Experts studied 3,500 white and 365 black women who received hormone therapy. They were found to have stage 1 to 3 breast cancer.
Black women were 1.6 times more likely to have the disease in their lymph nodes at diagnosis.
They are also 1.5 times more likely to have stage 3, but 2.6 times more likely to be mistakenly understated at diagnosis.
If the cancer was detected at an early stage, black women could have their tumor stage down by almost a factor of three. It might even disappear more than it did in white women.