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2017 Conference

Abstract Number: 562 | ID: 2017-562

Greenness and Breast Cancer in a US-Based Nationwide Prospective Cohort Study

Peter James(Harvard Medical School and Harvard Pilgrim Healthcare Institute, United States,, Jaime E. Hart(Harvard Medical School and Harvard T.H. Chan School of Public Health, United States), Kimberly Bertrand(Slone Epidemiology Center at Boston University, United States), Carla Bezold(Harvard T.H. Chan School of Public Health, United States), Trang VoPham(Harvard Medical School and Harvard T.H. Chan School of Public Health, United States), Rulla Tamimi(Harvard T.H. Chan School of Public Health and Harvard Medical School, United States), Francine Laden(Harvard T.H. Chan School of Public Health and Harvard Medical School, United States)
Background/Aim: Evidence is growing that exposure to nature may provide opportunities for physical activity, decrease exposure to pollution, increase social engagement, and enable psychological restoration. These factors have been hypothesized to influence breast cancer risk; however, few studies have directly assessed nature exposure and breast cancer incidence. We examined the association between residential satellite-based vegetation and breast cancer incidence using data from the prospective nationwide US-based Nurses’ Health Study II cohort.
Methods: We followed 109,643 women from 1989-2013. Cumulative average vegetation exposure was estimated using time-varying normalized difference vegetation index (NDVI) Advanced Very High Resolution Radiometer satellite data at ~1 km2 scale for each residence over follow-up. NDVI data from summer (July) was chosen to maximize variability. Incident invasive breast cancer cases were self-reported and confirmed by medical record review. We used Cox proportional hazard models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for age, calendar year, race, benign breast disease history, family history of breast cancer, age at menarche, height, body mass index (BMI) at age 18, current BMI, personal income, parity/age at first birth, menopausal status, mammography screening, smoking status, marital status, living alone, night shift work, diet (based on the Alternative Healthy Eating Index), and physical activity.
Results: We identified 3,458 incident breast cancer cases from 1989-2013. The average age of participants at baseline was 34.4 years and 95.5% of participants were white. In fully-adjusted models, participants living in the top quintile of cumulative average NDVI had a 13% lower risk of incident breast cancer (95% CI 0.75, 1.01, p for trend 0.02) compared to those in the bottom quintile.
Conclusions: Although further research is required to identify the mechanisms involved, our findings suggest that living in a neighbourhood with higher levels of greenness is associated with decreased risk of invasive breast cancer.