Why breast black cancer patients experience lower survival rates than other women

Oct 12 2005

Black women with stage I or II breast cancer are more likely than their counterparts of other races to abandon chemotherapy before completing their full course of treatment, according to a recent Columbia University Medical Center study.

Published in the Journal of Clinical Oncology, the findings shed new light on why breast black cancer patients experience lower survival rates than other women, despite a lower incidence.

"This study is the first to correlate early termination of chemotherapy with racial disparities in breast cancer outcomes," said Dawn Hershman, M.D., M.S., assistant professor of medicine and epidemiology at Columbia University College of Physicians & Surgeons and the Mailman School of Public Health, and the study's lead investigator.

Dr. Hershman and her research team set out to study the association between race and survival with duration of treatment and number of completed chemotherapy cycles. They analyzed the data of 472 stage I and II breast cancer patients enrolled in the tumor registry of the Henry Ford Health System, a large Detroit-area healthcare provider, between 1996 and 2001.

The investigators determined that women who discontinued treatment were more likely to be black and more likely to die than those who completed full chemotherapy cycles. Key findings include:

• Only 68 percent of black patients (136 out of 202 total) -- compared to 76 percent of white patients (206 out of 270 total) -- completed all prescribed cycles of chemotherapy.
• 93 percent of all white patients in the study group were alive five years after diagnosis; compared to 81 percent of black patients.
• A significant number of patients -- 130 out of 472 subjects, nearly 28 percent of the total study population -- did not receive complete treatment (defined here as less than 85 percent of the number of expected cycles).
• The overall five-year survival rate for the total patient population surveyed in this study was 88 percent. For the 130 patients who terminated chemotherapy early, the rate was only 74 percent.
• Being over 50 years of age, having stage II cancer (versus stage I), and a higher comorbidity score (obesity, other serious illnesses such as diabetes, chronic obstructive pulmonary disease, etc.), were associated with an increase of early treatment termination.
• Diabetes is strongly associated with incomplete treatment. Regardless of race, 44 percent of diabetic patients stopped treatment early, while only 26 percent of nondiabetic patients stopped early.
• "These findings confirm the vital need for breast cancer patients to complete the chemotherapy treatment cycles that are often essential to survival," said Dr. Hershman.

Many issues are thought to be a factor in poor compliance among black women: inadequate physician-patient communication and social-support networks, treatment toxicity, racial differences in drug metabolism, comorbidities and other health complications, e.g., lower white blood cell counts (an indication of a weaker immune state, which can cause delays in the administration of chemotherapy cycles).

"Further study is warranted to identify barriers to compliance. However, it's vital that all women are well-educated about the risks of terminating treatment early. In the long-run, improving the quality of breast cancer treatment may prove to be as important as screening and education."