Abstract 5252: Prospective cohort study of physical activity and lung cancer risk in the Black Women's Health Study
Authors: Samson Marsha , Nomura Sarah , Dash Chiranjeev , Bethea Traci , Rosenberg Lynn , Adams-Campbell Lucile 
Published: August 2018

Abstract
Background: Lung cancer is the second most common site of cancer among Black women. Black women have higher incidence rates of lung cancer despite having a lower smoking prevalence than their White counterparts. These differences are not well understood but may be due to differences in smoking behavior and other potential lung cancer risk factors (e.g., physical activity). Lower reported physical activity levels among Black women compared to White women could contribute to observed lung cancer disparities. Previous studies have shown a 20-50% lower risk of lung cancer among those who are physically active but overall, findings are equivocal. To our knowledge, no previous studies have examined the relationship between physical activity and lung cancer risk in Black women and few studies have examined the associations of physical activity with lung cancer risk stratified by smoking status.
Objective: The objective of this study is to evaluate the association between physical activity over time and lung cancer incidence in the Black Women's Health Study, and determine if tobacco use modifies this association. Methods: In this ongoing prospective cohort of Black women (analytic cohort n=46217), 291 cases of lung cancer were diagnosed between 1995 (baseline) and 2013. Questionnaire data, collected at baseline and updated every other year thereafter, were used to calculate recreational physical activity (walking for exercise, vigorous physical activity) and smoking history. The Anderson-Gill method was used as a time-varying analysis tool to continuously update exposures and covariates over time. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals (CIs). Results: At baseline, 65.5% of women were never smokers and 44% reported &lt;1 hr of vigorous physical activity per week. Women who reported any vigorous activity (≥1 hr/wk) had a lower, albeit not statistically significant, risk of lung cancer compared to women with no vigorous activity. In stratified analyses by smoking status, vigorous activity was inversely associated with lung cancer risk among never smokers (HR: 0.37; 95% CI: 0.15, 0.91), but was not associated with risk in former (HR: 1.39; 95% CI: (0.88, 2.21) or current smokers (HR: 1.06; 95% CI: 0.63, 1.77). Conclusion: Our findings suggest that intensity of physical activity may play a role in reducing lung cancer risk among Black women who had never smoked, but the number of lung cancer cases in that category was relatively small. No studies have examined the relationship between physical activity and lung cancer risk in black women and this relationship should be further explored to help reduce lung cancer disparities in the nation.
Citation Format: Marsha Samson, Sarah Nomura, Chiranjeev Dash, Traci Bethea, Lynn Rosenberg, Lucile Adams-Campbell. Prospective cohort study of physical activity and lung cancer risk in the Black Women's Health Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5252.