Does Utilization of Screening Mammography Explain Racial and Ethnic Differences in Breast Cancer?

18 April 2006 | Volume 144 Issue 8 | Pages 541-553

Background: Reasons for persistent differences in breast cancer mortality rates among various racial and ethnic groups have been difficult to ascertain.

Objective: To determine reasons for disparities in breast cancer outcomes across racial and ethnic groups.

Design: Prospective cohort.

Setting: The authors pooled data from 7 mammography registries that participate in the National Cancer Institute–funded Breast Cancer Surveillance Consortium. Cancer diagnoses were ascertained through linkage with pathology databases; Surveillance, Epidemiology, and End Results programs; and state tumor registries.

Participants: 1 010 515 women 40 years of age and older who had at least 1 mammogram between 1996 and 2002; 17 558 of these women had diagnosed breast cancer.

Measurements: Patterns of mammography and the probability of inadequate mammography screening were examined. The authors evaluated whether overall and advanced cancer rates were similar across racial and ethnic groups and whether these rates were affected by the use of mammography.

Results: African-American, Hispanic, Asian, and Native American women were more likely than white women to have received inadequate mammographic screening (relative risk, 1.2 [95% CI, 1.2 to 1.2], 1.3 [CI, 1.2 to 1.3], 1.4 [CI, 1.3 to 1.4], and 1.2 [CI, 1.1 to 1.2] respectively). African-American women were more likely than white, Asian, and Native American women to have large, advanced-stage, high-grade, and lymph node–positive tumors of the breast. The observed differences in advanced cancer rates between African American and white women were attenuated or eliminated after the cohort was stratified by screening history. Among women who were previously screened at intervals of 4 to 41 months, African-American women were no more likely to have large, advanced-stage tumors or lymph node involvement than white women with the same screening history. African-American women had higher rates of high-grade tumors than white women regardless of screening history. The lower rates of advanced cancer among Asian and Native American women persisted when the cohort was stratified by mammography history.

Limitations: Results are based on a cohort of women who had received mammographic evaluations.

Conclusions: African-American women are less likely to receive adequate mammographic screening than white women, which may explain the higher prevalence of advanced breast tumors among African-American women. Tumor characteristics may also contribute to differences in cancer outcomes because African-American women have higher-grade tumors than white women regardless of screening. These results suggest that adherence to recommended mammography screening intervals may reduce breast cancer mortality rates.

Editors' Notes Context Breast cancer mortality rates have fallen but still differ by race and ethnicity. One explanation might be differences in mammography use. Content These investigators linked data from mammography registries to tumor registries and showed that African-American and Hispanic women have longer intervals between mammography and are more likely to have advanced-stage tumors at diagnosis and to die of breast cancer than white women. However, in women with similar screening histories, these rates were similar regardless of race or ethnicity. Implications Differences in mammography use may explain ethnic disparities in the incidence of advanced-stage breast cancer and in mortality rates. —The Editors

 

Author and Article Information

From the University of California and San Francisco Veterans Affairs Medical Center, San Francisco, California; Group Health Cooperative, Seattle, Washington; RAND Corporation, Arlington, Virginia; National Cancer Institute, Bethesda, Maryland; University of Colorado Health Sciences Center, Denver, Colorado; University of Kentucky Prevention Research Center, Lexington, Kentucky; Cancer Research and Biostatistics, Seattle, Washington; and University of North Carolina, Pembroke, North Carolina.

Grant Support: By the Mount Zion Dean's Account, the California Breast Cancer Research Program, The Department of Defense Congressionally Directed Medical Research Programs, The National Cancer Institute (K07 CA86032), and National Cancer Institute–funded Breast Cancer Surveillance Consortium cooperative agreements (U01CA63740, U01CA86076, U01CA86082, U01CA63736, U01CA70013, U01CA69976, U01CA63731, U01CA70040.)

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: Rebecca Smith-Bindman, MD, Department of Radiology, University of California, 1600 Divisadero Street, San Francisco, CA 94115; e-mail, Rebecca.Smith-Bindman{at}Radiology.UCSF.edu.

Current Author Addresses: Dr. Smith-Bindman: Department of Radiology, University of California, San Francisco, 1600 Divisadero Street, Room C250, San Francisco, CA 94115-1667.

Dr. Miglioretti and Ms. Abraham: Group Health Cooperative Center for Health Studies, 1730 Minor Avenue, Suite 1600, Seattle, WA 98101.

Dr. Lurie: RAND Corporation, 1200 South Hayes Street, Arlington, VA 22202.

Dr. Ballard Barbash: National Cancer Institute, Applied Research Program, Division of Cancer Control and Population Sciences, 6130 Executive Boulevard, Bethesda, MD 20892-7344.

Dr. Strzelczyk: School of Medicine, University of Colorado Health Sciences Center, Denver, CO 80262.

Dr. Dignan: University of Kentucky Prevention Research Center, 2365 Harrodsburg Road, Suite B100, Lexington, KY 40504.

Dr. Barlow: Cancer Research and Biostatistics, 1730 Minor Avenue, Suite 1900, Seattle WA 98101.

Ms. Beasley: Department of Nursing, University of North Carolina Pembroke, 1 University Drive, Pembroke, NC 28372.

Dr. Kerlikowske: General Internal Medicine Section, Department of Veterans Affairs, University of California, San Francisco, 4150 Clement Street, 111A1, San Francisco, CA 94121.

Author Contributions: Conception and design: R. Smith-Bindman, D.L. Miglioretti, N. Lurie, R.B. Barbash, J. Strzelczyk, M. Dignan, W.E. Barlow, K. Kerlikowske.

Analysis and interpretation of the data: R. Smith-Bindman, D.L. Miglioretti, N. Lurie, L. Abraham, R.B. Barbash, W.E. Barlow, K. Kerlikowske.

Drafting of the article: R. Smith-Bindman, D.L. Miglioretti, N. Lurie, R.B. Barbash, M. Dignan, W.E. Barlow, K. Kerlikowske.

Critical revision of the article for important intellectual content: R. Smith-Bindman, D.L. Miglioretti, N. Lurie, R.B. Barbash, J. Strzelczyk, M. Dignan, W.E. Barlow, C.M. Beasley, K. Kerlikowske.

Final approval of the article: R. Smith-Bindman, D.L. Miglioretti, N. Lurie, R.B. Barbash, M. Dignan, W.E. Barlow, C.M. Beasley, K. Kerlikowske.

Provision of study materials or patients: M. Dignan, K. Kerlikowske.

Statistical expertise: R. Smith-Bindman, D.L. Miglioretti, L. Abraham, W.E. Barlow.

Obtaining of funding: R. Smith-Bindman, N. Lurie, K. Kerlikowske, D.L. Miglioretti, W.E. Barlow.

Administrative, technical, or logistic support: R. Smith-Bindman.

Collection and assembly of data: R. Smith-Bindman, L. Abraham, C.M. Beasley, K. Kerlikowske, D.L. Miglioretti.