Black-white disparity in physical performance among older women with newly diagnosed non-metastatic breast cancer: Exploring the role of inflammation and physical activity.

OBJECTIVE: To examine racial differences in physical performance among older women with newly diagnosed non-metastatic breast cancer and identify clinical, behavioral and biological factors that might contribute to such disparities.

METHODS: This is a cross-sectional study of women aged ≥65 years with newly diagnosed stage I-III breast cancer recruited from ambulatory oncology clinics at an academic center, between September 2010 and August 2015. Participants completed a Comprehensive Geriatric Assessment and laboratory testing for biomarkers of inflammation [interleukin-6 (IL6)] prior to receiving systemic treatment for cancer. The primary outcome was poor physical performance, defined as scoring ≤7 on the Short Physical Performance Battery, Yes or No. Logistic regression analyses were undertaken.

RESULTS: Among 135 women with mean age of 74.8 years (SD = 6.9), 31% were African-American (AA), and 33% had poor physical performance. Controlling for age, education, comorbidities and geriatric syndromes, participants with poor physical performance were more likely to be AA [versus (vs.) Non-Hispanic Whites (NHW)], odds ratio (OR) = 3.10, 95% confidence interval (CI) = 1.18-8.15. Controlling further for physical activity (PA) attenuated the racial disparity in physical performance (OR = 2.50, CI = 0.91-6.84). Lastly, controlling for IL6 further diminished the racial disparity in physical performance (OR = 1.93, CI = 0.67-5.56). In adjusted models, PA and IL6 explained 29% and 38%, respectively, of the racial disparity in poor physical performance.

CONCLUSION: Among older women with newly diagnosed non-metastatic breast cancer, poor physical performance was prevalent and AA were disproportionately affected. Less engagement in physical activity and subclinical inflammation partly contributed to this disparity.