From Cancer Research UK:
"Black British women in Hackney, East London, are diagnosed with breast cancer 21 years younger than white British women, according to a Cancer Research UK study published online in the British Journal of Cancer. In the first UK study to look at the patterns of breast cancer in black British women, the researchers studied 102 black women and 191 white women diagnosed with breast cancer at Homerton University Hospital in Hackney, East London, between 1994 and 2005. They found the black patients were diagnosed with breast cancer at an average age of 46 while the white patients were diagnosed at an average age of 67."
More here, including a link to the full report.