Urban green spaces and childhood leukemia incidence: A population-based case-control study in Madrid.

Abstract Background Childhood leukemia is the most common childhood cancer. To date, few risk factors related to predisposition have been identified; therefore, new hypotheses should be considered. Objective To explore the possible relationship of residential proximity to urban green spaces on childhood leukemia. Methods We conducted a population-based case control study in the metropolitan area of Madrid from 2000 to 2015. It included 383 incident cases and 1935 controls, individually matched by birth year, sex and area of residence. Using the geographical coordinates of the participants’ home residences, we built a proxy for exposure with four distances (250 m, 500 m, 750 m and 1 km) to u…