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Main Finding(s): Minority women were more likely to have aggressive subtypes of breast cancer and were more likely to receive non-guideline concordant treatment when compared with non-Hispanic white women.
Journal in Which the Study was Published: Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
Author: Lu Chen, MPH, a researcher in the Public Health Sciences Division at Fred Hutchinson Cancer Research Center in Seattle.
Background: It has been consistently observed that minority women, especially African Americans, Hispanic whites and American Indians, are more likely to be diagnosed at advanced stages of breast cancer, less likely to receive recommended treatment regimens, and more likely to die of the disease. Previous studies have addressed the disparities by stage of disease and survival rates, but did not characterize them by subtypes, Chen said.
How the Study Was Conducted: Chen and colleagues drew on data from 18 U.S. population-based cancer registries participating in the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute. The data include demographic characteristics, stage, tumor grade and size, primary treatment, and health insurance status of 102,064 U.S. women, plus their tumor subtypes, hormone receptor (HR) status, and human epidermal growth factor 2-neu (HER2) status.
Results: The researchers found that non-Hispanic white women were more likely to have smaller tumors, and more likely to have the less-aggressive HR+/HER2- subtype of breast cancer, compared with African-American women, who were more likely to have large tumors, more likely to have the aggressive triple-negative breast cancer, and 40 to 70 percent more likely to be diagnosed at stage 4 of all subtypes of breast cancer. Hispanic white women were 30 to 40 percent more likely to be diagnosed at stage 2 and/or stage 3 across all breast cancer subtypes.
The disparities continued across all stages of disease. Compared with non-Hispanic whites, women of all other racial and ethnic groups were more likely to be diagnosed with more advanced stages of breast cancer, researchers found.
They also found that compared with non-Hispanic white women, African-American women were 30 to 60 percent more likely to receive non-guideline concordant (inappropriate) treatment across all subtypes except HR-/HER2+, and Hispanic white women were 20 to 40 percent more likely to receive inappropriate treatment (except HR-/HER2+ and triple-negative cases). Asians and Pacific Islanders showed no disparity with non-Hispanic white patients in receiving guideline-concordant treatment. American Indian and Alaska Native women showed some disparities, but Chen noted that the sample size of this group was small, undermining the ability to detect statistically significant differences. Disparities persisted after adjusting for insurance status, suggesting that other factors also play important roles.
Author Comment: "We found that there is a consistent pattern of late diagnosis and not receiving recommended treatment for some racial and ethnic groups across all breast cancer subtypes," Chen said in an interview. In recent years, increased information about the molecular and genetic characteristics of breast cancer has helped improve treatment for the disease. "The treatment for breast cancer is currently dependent on the type of breast cancer, defined by the estrogen receptor, progesterone receptor, and HER2 status," Chen said. "This is the reason why we think it's important to look at the disparities by subtype."
Chen added, "Given the racial and ethnic disparities, targeted, culturally appropriate interventions in breast cancer screening and care have the potential to reduce the disparities and close the existing survival gaps."
Limitations: Chen said limitations of the study include: Exclusion of 14 percent of the women in the original sample due to missing data, potential misclassification and variations in the data gathered by cancer registries, and a short follow-up time between the collection of data and the completion of the study
Funding & Disclosures: This study was funded in part by the National Cancer Institute. Chen declares no conflicts of interest.
About the American Association for Cancer Research
Founded in 1907, the American Association for Cancer Research (AACR) is the world's oldest and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 35,000 laboratory, translational, and clinical researchers; population scientists; other health care professionals; and patient advocates residing in 101 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis, and treatment of cancer by annually convening more than 30 conferences and educational workshops, the largest of which is the AACR Annual Meeting with almost 19,300 attendees. In addition, the AACR publishes eight prestigious, peer-reviewed scientific journals and a magazine for cancer survivors, patients, and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the Scientific Partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration, and scientific oversight of team science and individual investigator grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and other policymakers about the value of cancer research and related biomedical science in saving lives from cancer. For more information about the AACR, visit http://www.