Black women both develop breast cancer at an earlier age and are more likely to die from it according to a new study published in the British Journal of Cancer.

The study, conducted using patient data from Homerton University Hospital in Hackney from 1994 to 2005 found that black women were diagnosed with breast cancer a massive 21 years earlier on average than white women. The study also suggested a poorer survival rate amongst black women diagnosed with breast cancer and that the cancers tended to be more aggressive and less likely to respond to some of the newer, specialized cancer treatments such as Herceptin.

The study consisted of 293 participants, of which 102 were black women. The black women averaged just 46 years at the age of diagnosis, compared to the 67 years for white women. While the study was small and will need to be replicated in larger studies, the massive differences in the age when breast cancer is diagnosed have been described as “interesting” by the study’s authors.

According to study author Dr Rebecca Bowen of the Institute of Cancer And Cancer Research UK Clinical Centre, “We think the differences in the way tumours of black and white women behave can be put down to the biological differences between the two ethnic groups.”

This is the first major study on ethnicities role in breast cancer in the United Kingdom because until recently ethnicity data was not collected by cancer registries. In the United Studies however, small studies have also suggested young African-American women are more susceptible to breast cancer, particularly the more aggressive forms of the illness.

Breast cancer is the second most common form of cancer and the most common in women. It is the third most deadly form of cancer with only lung and colo-rectal cancer responsible for more deaths each year.