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November 13, 2015

African-American Breast Cancer Risk on the Rise: What immediate changes can be made to help slow incidence?

An invited commentary by Dr. Cynthia Owusu on the recent report released by the American Cancer Society on the rising incidence of breast cancer in African-American women. 

Breast cancer is the most common cause of invasive cancer among women and will account for 231,840 new cases of invasive cancer in 2015. It is also the leading cause of cancer deaths among women with 40,290 cancer deaths expected in 2015. 

Racial disparities in breast cancer incidence and mortality have been noted since 1975, with African-Americans having a lower incidence but a higher five-year mortality compared to non-Hispanic Whites. Data from the American Cancer Society's 2015-2016 Breast Cancer Facts and Figures indicate that from 2008 to 2012, the age adjusted incidence of newly diagnosed breast cancer was on average 128.1 per 100,000 among Non-Hispanic Whites, compared to 124.3 per 100,000 in African-Americans. However, breast cancer mortality rates during the same period were estimated to be 21.9 per 100,000 among Non-Hispanic Whites and 31 per 100,000 for African-Americans. These racial disparities are even greater in Cuyahoga County, Ohio, where mortality rates of breast cancer in African-American women are greater than those observed in Caucasian women and, interestingly, where the incidence and mortality rates in both ethnic groups exceed national averages based on data from the Ohio Department of Health. This trend in racial disparities in breast cancer incidence and mortality have persisted in spite of recent advances in breast cancer management, and now appears to have reached an unfortunate milestone with African-Americans just as likely to be diagnosed with a new breast cancer compared to Non-Hispanic Whites. 

Recent sobering statistics from the American Cancer Society's 2015-2016 Breast Cancer Facts and Figures indicate that between 2008 to 2012 breast cancer incidence rates among African-Americans increased by 0.4 percent each year while it remained stable among Non-Hispanic Whites. Finally, in 2012 breast cancer incidence rates among African-Americans and Non-Hispanic Whites finally converged. These findings have recently been discussed in an interesting article in the "New York Times", A Grim Cancer Milestone for Black Women. Given the increasing incidence of breast cancer and the higher breast cancer death rate among African-Americans, breast cancer mortality rates among African-American women are likely to increase over the coming years and present a challenging problem.  The NY Times article discusses possible causes for the increase in incidence of breast cancer among African-American women and singles out obesity and changing reproductive patterns among African-Americans as contributory factors. 

Obesity is a significant public health problem. Two-thirds of the US population is currently overweight or obese, with African-Americans having the highest obesity rate compared to any other racial/ethnic group. Obesity is associated with increased breast cancer risk and mortality and may be linked to cancer through insulin resistance and inflammation. Unfortunately, African-American breast cancer survivors have lower rates of physical activity and tend to gain more weight compared to non-Hispanic Whites, which may be contributing to their poorer survival. 

It is also important to note that physical activity is independently associated with improved breast cancer outcomes, beyond its positive impact on obesity. Regular physical activity after breast cancer diagnosis is associated with improved breast cancer-specific and overall survival. A meta-analysis of over 12,000 women with breast cancer, conducted by Ibrahim, EM, et al, and published in Medical Oncology in 2011, showed that post-diagnosis physical activity reduced breast cancer recurrence by 24 percent, breast cancer mortality by 34 percent, and all-cause mortality by 41 percent. Despite these and many other health benefits, according to a study of 1700 women by Hair, et al, and reported in Cancer in 2014, only about 35 percent of breast cancer survivors ages 20-74 years engage in the US Department of Health and Human Services and the American Cancer Society's recommended amount of physical activity of 150 minutes of aerobic exercise per week.  Rates of physical inactivity were particularly high among African-American breast cancer survivors who were about one and half times more likely not to meet guideline recommended physical activity compared with Non-Hispanic Whites.   

Taken together, it is obvious that promotion of healthy behaviors will be critical to addressing health disparities among African Americans. There is an urgent need to explore the potential role that modifiable behavioral risk factors such as diet and physical activity may play in explaining and reducing racial disparities in breast cancer mortality. Together with my collaborators from University Hospitals and Case Western Reserve University School of Medicine, Cleveland Clinic, Metrohealth Medical Center and The Gathering Place, we have recently received a 2.8 million grant from the National Institute on Minority Health and Disparities to conduct a five-year study that aims to develop a culturally-sensitive physical activity program that will foster initial enrollment and engagement in physical activity among women 65 years and older with breast cancer, particularly African-American women and women of lower socio-economic status. The study will examine the impact of physical activity on body composition (obesity), physical function and biomarkers associated with higher breast cancer recurrence such as inflammatory cytokines, insulin and sex hormones. Over the long term this program will be extended to African-American breast cancer survivors of all ages with an ultimate long-term goal to reduce racial disparities in breast cancer outcomes by targeting modifiable risk factors such as obesity and physical inactivity.

The grim milestone reached by African-American women and reported by the American Cancer Society underscores the urgent need to address racial disparities in breast cancer and calls for urgent action. Targeting modifiable risk factors such as obesity and physical inactivity among African-American breast cancer survivors will go a long way in helping to reduce the racial gap in breast cancer outcomes and calls for physical activity to be incorporated into models of breast cancer care, not for just African-American but for all patients. To this end oncologists should routinely ask their patients about physical activity or lack thereof and make appropriate recommendations or referrals.

Cynthia Owusu, MD is a geriatric oncologist at UH Seidman Cancer Center and Associate Professor in the Division of Hematology and Oncology at the CWRU School of Medicine. She is also a member of the Case Comprehensive Cancer Center.