Black-White disparities widening in US breast cancer deaths

NEW YORK  — In the largest cities in the US, death rates from breast cancer have dropped across the board over 20 years, but far less so for Black women than Whites, according to a new analysis. 

The widening survival gap is likely due to differences in the quality of healthcare and access to it, researchers contend, because health factors alone cannot explain the changes over two decades.

"The advancements in screening tools and treatment which occurred in the 1990's were largely available to White women, while Black women, who were more likely to be uninsured, did not gain equal access to these life-saving technologies," lead author Bijou Hunt, an epidemiologist at Mount Sinai Hospital in Chicago, told Reuters Health in an e-mail.

Past research has examined racial differences in survival for specific cancers and for cancer in general and found at least some could be explained by biology. High blood pressure, diabetes and other health problems that both worsen cancer outcomes and are more common among Blacks have received some of the blame.

Black women are also more likely than Whites to have aggressive breast tumours that don't respond to the most effective treatments. This basic difference in cancer genetics is another reason given for differing survival when it comes to breast cancer.

To assess changes in survival trends on a national level, Hunt and her colleagues looked at mortality rates in the largest US cities at four different time points: 1990-1994, 1995-1999, 2000-2004 and 2005-2009.

They found that during the 20-year span, deaths from breast cancer fell overall — by 13 per cent for Black women and by 27 per cent for White women. While a gap was already present in the early 1990s, it widened considerably with time.

The team's analysis, published in the journal Cancer Epidemiology, found that during 1990-1994, the rate of breast cancer deaths was 17 per cent greater among Blacks than among Whites. This steadily increased to 30 per cent, then to 35 per cent and finally to 40 per cent in the last time period they looked at.

The disparity was particularly striking in Memphis, Tennessee, where the rate of breast cancer deaths among Blacks was 27 per cent higher than among Whites in 1990-1994 and ballooned to more than two-fold higher by 2005-2009.

In Los Angeles, the mortality rate among Blacks was 24 per cent higher than among Whites in 1990-1994 and 71 per cent higher in 2005-2009.

Wichita, Kansas, which had no significant differences in mortality rates among Blacks and Whites at the first time point studied, had a two-fold increased rate of deaths among Blacks in 1995-1999, which fell to a 57 per cent greater mortality rate among Blacks by the most recent time point.

Most, but not all, of the 41 cities included in the final analysis saw an increase in racial disparities during the study period. This was not true of New York, however, the largest city included. The disparity in New York was about the same at the first and last time points examined, with an 18 to 19 per cent greater mortality rate among Blacks than Whites, the researchers note.

Several other large cities, including Minneapolis, Miami, Portland and Las Vegas, did not have any significant differences at all in mortality rates between Blacks and Whites at any of the four time periods examined.

The growing gap in breast cancer deaths among Blacks versus Whites was largely caused by a steeper drop in breast cancer deaths among Whites than among their Black counterparts, Hunt and her colleagues point out.

Sixteen states experienced a greater than 20 per cent decrease in the White mortality rate, but a less than 10 per cent decrease in mortality among Blacks, the researchers report.