Differences in breast cancer survival rates between races are most apparent in the advanced stages of the disease, new American research suggests.
Women of African origin had poorer five-year survival rates and more advanced disease at the time of diagnosis than white women.
The researchers from Columbia University Medical Center found an ethnic gap in outcomes after accounting for variations in tumour size and the number of lymph nodes affected.
The mortality rate among African-American women was up to 56 per cent higher than that for whites.
However, they acknowledged that "the factors that prevent black women from receiving the same quality of care as white women may be exacerbated by the more complex treatment regimens used for more advanced breast cancer".
Survival rates within the same stage can vary by as much as 40 per cent depending on the number of lymph nodes affected.
The scientists said that their findings imply that non-clinical factors affect patient prospects.