Natural outdoors environments and prostate and breast cancer risk: a case-control in Spain

Abstract

Introduction: Mechanisms explaining the beneficial effect of natural outdoor environment (NOE) include physical activity and stress restoration. Epidemiological data support the protective effect of physical activity on prostate and breast cancer. The aim of this analysis is to investigate the association between NOE and prostate and breast cancer. Methods: We collected residential information for 937 prostate cancer cases and 1050 sex, age and area matched controls and 1412 breast cancer cases and 1628 1050 sex, age and area matched controls between 2008-10 in 11 provinces (19 hospitals) of Spain. We geocoded the longest residence of each participant and we assigned four indicators of exposure to NOE within 300 m buffer: Access to major green spaces (i.e. forest or park >25 Ha) according to CORINE Land Cover 2006; access to urban green areas (>0.5 Ha) and to agricultural areas (>0.5 Ha) both according Urban Atlas; and surrounding greenness according to the average of the Normalized Difference Vegetation Index (NDVI). Detailed information on covariates was obtained. We used mixed models with hospital as random effect. All models were adjusted for age, socio-economical status (individual and area) and degree of urbanization. Results: Reduced risk of prostate cancer was observed among those with access to major green spaces and access to urban green spaces [OR (95%CI)=0.49 (0.39-0.62) and OR=0.23 (0.17-2.29), respectively]. Access to agricultural areas was associated with increased risk of prostate cancer [OR=1.46 (1.12-1.90)]. No association was detected for surrounding greenness [OR=0.99 (0.89-1.11)]. Reduced risk of breast cancer was observed among those with access to urban green areas [OR=0.71 (0.55-0.91)]. Access to major green spaces and access to agricultural areas was associated with increased risk of breast cancer [OR (95%CI)=1.18 (0.99-1.42) and OR=1.22 (0.96-1.54), respectively]. Increased risk was also associated with surrounding greenness [OR (95%CI)=1.34 (1.19-1.52)]. All results were consistent after adjusting for other potential confounders. There was no suggestion for mediation by physical activity. Conclusion: The association between access to NOE and risk of prostate and breast cancer depends on the type of NOE. Access to urban green spaces is associated with reduced risk of both prostate and breast cancer, whereas access to agricultural is associated with increased risk.