Racial gap in breast cancer survival rates remains

Differences at diagnosis, not differences in treatment, explain more about the discrepancy.

The two-decade-long divide in breast cancer survival rates among black and white women has not budged, and gaps in treatment explain only part of the story, a new study says.
Despite declines in breast cancer deaths over the past 20 years and strides in breast cancer diagnosis and treatment, black women are 40% more likely to die of cancer than white women, according to the Centers for Disease Control and Prevention.
For years, researchers have scratched heads over why the racial disparity exists, suggesting differences in screening, existing health problems, socioeconomic status and treatment.
But the low survival rate can't be explained solely by the types and frequency of treatment, says a new study, published Tuesday in the Journal of the American Medical Association,
The study suggests that characteristics at diagnosis explain the differences in survival, not differences in the type, duration and frequency of treatment. Black patients had poorer health at diagnosis, including more advanced disease, worse biological features of the disease, and larger tumor size.
"Can you blame the oncologists? Probably not. But what we are saying is that in order to improve diagnoses, we have to turn to primary care," says Jeffrey Silber, study author and director of the Center for Outcomes Research at the Children's Hospital of Philadelphia. "This is an issue of prevention."
Silber is also a professor of pediatrics, anesthesiology, critical care and health care management at the University of Pennsylvania.
Breast cancer is the second-leading cause of cancer deaths among women (after lung cancer), killing about one in 36 women in the USA annually. Death rates have been declining since the 1980s as a result of earlier detection through screening, increased awareness and improved treatment, but they have leveled off in recent years.
In the study, researchers compared survival rates of more than 7,000 black women over 65 with three sets of white patients who were matched based on demographics such as age; year of diagnosis; the state of their health upon diagnosis, including existing health problems and the size, stage and grade of tumors; and treatment, such as surgery, radiation therapy and chemotherapy. The women were all insured by Medicare to control for the effect of socioeconomic background.
When researchers controlled for demographics, there was a 12.9% difference in five-year breast cancer survival. That difference declined to 4.4% after controlling for demographic characteristics and health status upon diagnosis. Adding on the third layer — treatment characteristics — shrunk the likelihood of survival down to a difference of 0.81%, suggesting the type and frequency of treatment accounts for only a small portion of the racial disparity.
This comprehensive matching system allowed researchers to eliminate major biases that affect analysis, wrote Jeanne Mandelblatt and her colleagues in an editorial accompanying the story. Mandelblatt is the associate director of population sciences at Georgetown University.
Though the study tracked patients diagnosed between 1991 and 2005 and through 2009, the results likely hold true today, Silber says, adding that advances in treatment — however startling — can't offset the disparities in diagnosis.
Still, 12.6% of black patients did not receive treatment, compared with 5.9% of whites. Black patients also had longer average times between diagnosis and treatment. Prior to diagnosis, many black patients also received less adequate primary care than white patients in the same demographic, the study says.
It's possible that the role of treatment could be understated, especially since the database that collects records of all Medicare users diagnosed with cancer through 2009 — SEER-Medicare (Surveillance, Epidemiology, and End Results) — doesn't include details on the doses, intensity and completion of dose cycles.
"We all agree advances in treatment are important and any disparities need to be eliminated," Silber says. "But eliminating that disparity isn't the solution. We need to concentrate on diagnosis."