Race and Ethnicity Affect Breast Cancer Diagnosis and Survival

Javaid Iqbal, MD, MSC (Candidate) Institute of Medical Sciences, and Women’s College Research Institute/Women’s College Hospital University of Toronto, Toronto CanadaMedicalResearch.com Interview with:
Javaid Iqbal, MD, MSC (Candidate)
Institute of Medical Sciences, and
Women’s College Research Institute/Women’s College Hospital
University of Toronto, Toronto Canada


What is the background for this study? What are the main findings?

Dr. Iqbal: A woman’s racial/ethnic background predicts her participation in breast cancer control program (i.e., awareness and screening). The ultimate objective of breast cancer control program is to detect cancer at an optimal stage, which is stage I, because women with stage I breast cancer survive longer. Given the racial/ethnic diversity of North America, this poses questions such as “what predicts stage I breast cancer in the multiethnic North American population?”, “what predicts its survival?”, and “does a woman’s ethnic background plays a role in predicting an early stage, and survival?”

We studied 373,563 women diagnosed with invasive breast cancer in the United States between 2004 and 2011. We followed these women for 7 years and recorded whether or not they died of breast cancer, or whether they are still alive. We then divided all women into different ethnic groups, in particular white, black, Chinese, Japanese, and Indian/Pakistani (South Asian). For each racial/ethnic group, we estimated proportions of women who were diagnosed with stage I breast cancer, and risk of death at 7 years. Our aim was to determine if the racial/ethnic differences in early stage breast cancer, and its survival were better explained by intrinsic biological differences in tumor characteristics, or by differences in early-detection of breast cancer.

We found that a woman’s racial/ethnic background predicted the diagnosis of stage I breast cancer, as well as her risk of dying at 7 years after breast cancer. A black woman was less likely than a white woman to be diagnosed with stage I breast cancer. A black woman was also more likely than a white woman to die of stage I breast cancer 7 years after her diagnosis. The Japanese and Chinese women were more likely than white women to be diagnosed with stage I breast cancer. The risk of death at 7 years was lowest for Indian or Pakistani (South Asian) women. Furthermore, even for small sized (2.0) breast cancers the risk of death at 7 years was higher for black women (9%), compared to white women (5%). Compared to white women, small sized breast cancers in black women were more aggressive at diagnosis, and had spread to lymph nodes and other organs.

What should clinicians and patients take away from your report?

Dr. Iqbal: Women should recognize the importance of adherence to breast cancer awareness and screening recommendations based on their individualized risk of breast cancer. For instance, women who are at high-risk, or an intermediate risk (based on their family history, reproductive history, ethnicity etc.) may need cancer screening at an earlier age compared to low-risk women. However, women should also adapt healthy diet and life-styles, which can potentially play a role in defining their risk, and outcome of breast cancer. Lastly, every effort should be made to avoid treatment delays in ethnic groups who are at high-risk of survival disparities (such as African Americans).

What recommendations do you have for future research as a result of this study?

Dr. Iqbal: Our research shows that the disparities between black and white are not entirely due to the lack of access to healthcare. While breast cancer awareness and screening are important in early-detection of breast cancer, other factors such as intrinsic genetics, biology, environmental and life-style factors may also play a role. This area is relatively unexplored and requires further research.

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