Greenspace exposure and cancer incidence in the Gazel Cohort

Abstract

Background: Exposure to greenspace has been suggested to be associated with lower cancer incidence; however, the evidence is still very scarce, and controversial. Here, we reported the association between exposure to greenspace at any site and site-specific (breast, bladder, colorectal, prostate, lung and skin) cancer incidence in the French GAZEL cohort.Method: We used 27 years follow-up data for 19,360 out of 20,625 enrolled participants in 1989 and assessed their exposure to greenness using satellite-derived Normalised Difference Vegetation Index (NDVI) within several buffers, and residential proximity to urban greenspaces, agricultural and forest lands using Corine Land Cover data. We used extended Cox model controlled for time-varying personal and area-level variables, with age as time scale and a ten-year lag. We stratified according to urban-rural area of the participants’ residence over follow-up.Results: Over the 294,371 person-years of follow-up (mean age at enrolment: 43.7; 27.1% female), we registered 3,689 cases of cancer. We found an increased risk for all-sites cancer with an inter-quartile range (IQR) increase of greenness exposure for all buffers, with a hazard ratio (HR) of 1.08, 95%CI (1.03: 1.13) for the 100m buffer. We also found a positive association of all-sites cancer with each km of decreasing distance to agricultural lands (HR: 1.04; 95% CI: 1.02: 1.07) and to forests (HR:1.03; 95% CI: 1.01: 1.05), but nothing with urban greenspaces. The cancer site-specific analyses showed a negative association between breast cancer and higher greenness within 100m (HR: 0.88; 95% CI: 0.76: 1.02), and no associations between any other site-specific cancers. Stratified analyses on rurality did not show any difference.Conclusion: Our study identified an increased risk of all-site cancer associated with increased greenness and proximity to agricultural lands and forests, whatever the level of rurality. Our findings are less clear for site-specific cancers.