This study is unique because there are previous studies on white women but very few on black women and so it would benefit.
Lead researcher Dr. Lynn Rosenberg of Boston University along with colleagues studied and examined data of 32,000 women aged 40 or older from the Black Women's Health Study during 1995 and 2003 to examine the association of hormone exposure and risk of breast cancer.
The results were that black women who had used hormone for 10 or more years increased their risk of breast cancer by 58 percent. In lean women, the risk was even greater, three times higher.
Thus it is higher compared to white women.
The explanation could be that leaner women are just not well prepared to handle high doses of hormone they take for the therapy because their levels of hormones are usually lower than those who have heavier weight.