In an analysis of 5-year survival rates among black and white women diagnosed with breast cancer between 1991 and 2005, black women continued to have a lower rate of survival. Most of the difference was related to factors that include poorer health of black patients at diagnosis and more advanced disease, rather than treatment differences.
The study, published in JAMA (2013; 310(4):389-397), explained that researchers in the United States have been keenly aware for 20 years of racial disparities in survival among women with breast cancer. The study compared 7,375 black women aged 65 years and older diagnosed between 1991 to 2005 and three sets of 7,375 matched, white control patients selected from 99,898 white, potential control patients. The patients all received follow-up through December 2009. The black case patients were matched to three white control populations based on demographics, presentation, and treatment.
The research team, led by Jeffrey H. Silber, MD, PhD, of the Children’s Hospital of Philadelphia in Pennsylvania, found that the absolute difference in five-year survival (blacks, 55.9%; whites, 68.8%) was 12.9% in the demographics match. After matching patients on presentation characteristics, the absolute difference in 5-year survival was 4.4% and 3.6% lower for blacks than for whites matched also on treatment.
Regarding differences in treatment by race, overall, 12.6% of black patients did not have evidence of receiving any treatment for their breast cancer, compared with 5.9% of whites. The average time from diagnosis to treatment was longer among blacks than among demographics-matched whites, at 29.2 days versus 22.5 days.
Blacks were also more likely to have long delays in treatment: 5.8% of blacks did not initiate treatment within 3 months from diagnosis, compared to 2.5% of white patients. Blacks also received breast-conserving surgery without any other treatment more often than presentation-matched whites (8.2% versus 7.3%). The authors stated that the differences in survival associated with treatment differences only accounted for 0.81% of the 12.9% survival difference.
Based on demographically matched patients, blacks had less evidence of at least one primary care visit, lower rates of breast cancer screening, and lower rates of colon cancer and cholesterol screening than matched whites. The authors stated that the racial disparity in survival may be difficult to eliminate unless differences in presentation can be reduced. The authors added that black patients also have more unrelated comorbid conditions, and these other health problems may blunt the effectiveness of cancer treatment for blacks.