Background: In the U. S., age-adjusted breast carcinoma mortality rates among white and African-American women have been diverging during the last 20 years. Some investigators speculate that the widening disparity is due to inequalities in access to healthcare, with African Americans having less access to necessary healthcare and improved therapies. Others argue that differences in tumor biology or some extrinsic influences on cancer etiology and behavior may account for the widening disparity. To examine this issue further, the authors compared trends in survival among white and African-American women diagnosed with breast carcinoma in the U. S. Department of Defense (DoD), an equal access healthcare system.
Methods: The medical records of all women diagnosed with primary breast carcinoma between 1980-1999 were retrieved from the U. S. DoD Automated Central Tumor Registry (ACTUR). Variables selected for further analysis were date of diagnosis, date of birth, vital status and date of death if applicable, race (black, white, and others), and stage of tumor. Because the database does not contain causes of death, overall survival was investigated. The effect of year of diagnosis and race on overall survival was analyzed using the Cox proportional hazards model stratified by age at diagnosis (1-year age groups). Calculations were performed separately by disease stage for all stages combined and stratified by stage. Statistical analyses were performed using the statistical software package SAS.
Results: After deleting observations with missing or implausible information regarding patient age, gender, and follow-up time, the final dataset was comprised of 23,612 women with primary breast carcinoma. The survival of African-American women compared with white women demonstrated an increasing ratio with calendar period. Although the hazard ratio was 1.269 for women diagnosed with breast carcinoma during the calendar period 1980-1984, it increased to 1.849 for those diagnosed between 1995-1999, which is a ratio of 1.46. For this period, the interaction between race and period was found to be significant (P = 0.04).
Conclusions: The results of the current study demonstrated that breast carcinoma survival rates among white and African-American patients, adjusted for age and stage, are diverging in the U. S. DoD healthcare system. Thus, inequalities in access to healthcare most likely are not solely responsible for the widening racial disparities in outcome reported among women diagnosed with breast carcinoma.
Copyright 2003 American Cancer Society.