Five-year survival rates among African American and white women with breast cancer have not changed substantially between 1991 and 2005, according to a study appearing in a recent issue of JAMA.
African American women continued to have a lower 5-year survival rate than white women (55.9% vs 68.8%). After matching with regard to presentation characteristics, the absolute difference in 5-year survival was 4.4% and was 3.6% lower for African American women compared with white women, who were also matched based on treatment.
Over the 20 years that researchers have been aware of these disparities, a number of potential reasons have been suggested, including differences in screening, presentation, comorbid conditions at the time of presentation, tumor biology, stage of disease, treatment, and socioeconomic status.
For the study, Jeffrey Silber, MD, PhD, of the Children's Hospital of Philadelphia in Pennsylvania, and colleagues examined the extent of racial differences in breast cancer survival in the Medicare population and the reasons for the disparity. They compared 7375 African American women aged 65 years and older who were diagnosed between 1991 and 2005 and 3 sets of 7375 matched white control patients using data from 16 US Surveillance, Epidemiology, and End Results (SEER) sites in the SEER-Medicare database. The African American patients were matched to the white control populations based on demographics (age, year of diagnosis, and SEER site), presentation (demographic variables plus patient comorbid conditions and tumor characteristics such as stage, size, grade, and ER status), and treatment (presentation variables plus details regarding surgery, radiotherapy, and chemotherapy).
In the study, 12.6% of African American patients did not demonstrate evidence of having received any treatment compared with 5.9% of white patients. In addition, the average time from diagnosis to treatment was 29.2 days for African American patients versus 22.5 days for demographically matched white women. African American patients also were more likely to have long delays in treatment; 5.8% did not initiate treatment within the first 3 months of diagnosis compared with 2.5% of white patients. At the same time, black women more often underwent lumpectomy without receiving any other treatment compared with presentation-matched white women (8.2% vs 7.3%).
Nevertheless, differences in survival associated with treatment differences only accounted for 0.81% of the 12.9% survival difference, the authors note.
In terms of presentation, African American women had significantly less evidence of at least 1 primary care visit than white women (80.5% vs 88.5%), significantly lower rates of screening (23.5% vs 35.7%), and significantly lower rates of screening for both colon cancer and cholesterol levels.
Silber et al note that the results suggest it may be difficult to eliminate racial disparities in survival without reducing the differences in presentation. If those differences were reduced, African American women would be diagnosed with less advanced disease, they add.