The higher death risk for African American women with metastatic breast cancer persists in clinical trials where overall responses to therapy are similar, according to a report in the June 1st Journal of Clinical Oncology.
"By controlling for treatment and eligibility, clinical trials remove many of the factors which can confound racial disparities in cancer" such as access, health insurance, and treatment, Dr. Blase N. Polite from University of Chicago, Chicago, Illinois told Reuters Health. "This allows us to focus on a smaller set of factors which may explain at least a portion of the survival differences that are still apparent even in this highly controlled setting."
Dr. Polite and colleagues examined racial differences in clinical outcomes and the potential reasons behind those differences in the setting of two large multicenter metastatic breast cancer trials.
African American women were more likely than white women to be receiving second line therapy, to be younger and premenopausal, and to have estrogen receptor-negative tumors, the authors report.
Median overall survival was shorter for African American patients (14.3 months) than for white patients (18.7 months), the researchers note, but tumor response did not differ by race overall (30 per cent versus 31 per cent, respectively).
After adjusting for all predictor variables, African American patients continued to have a 24 per cent increased hazard of death compared with white patients.
In addition to race, other variables significantly related to survival included line of therapy, estrogen receptor status, performance score, age, and pretreatment platelet count.
African American women also had a significantly higher incidence of treatment-related anemia, thrombocytopenia, and neutropenia, the investigators say, whereas white patients had a slightly higher hazard of developing grade three or higher lymphocytopenia.
"Certainly there is an array of factors that could be listed; however, the two that I believe deserve increased focus are the differences in comorbidities that impact survival and can potentially be intervened upon," Dr. Polite said. "Also, we must continue to examine potential genetic differences specifically as they relate to the so called triple negative or basal like tumors, which we know are more prevalent among young African American women and which may require different therapies."
Dr. Polite continued: "As part of the next Cancer and Leukemia Group B metastatic breast cancer trial, we will be collecting much more detailed information on comorbidities to determine the importance of conditions such as diabetes or hypertension in explaining survival differences. If these factors prove to be important, then perhaps it will encourage oncologists and primary care physicians to keep a greater focus on managing these comorbidities even among patients who have metastatic breast cancer."
J Clin Oncol 2008;26:2659-2665
