Physical inactivity and cancer: from evaluation of etiological evidence to public health impact

Abstract

Purpose: To investigate the current evidence on the association between physical inactivity and cancer incidence/mortality (Study 1) and the impact of this relationship on public health in Brazil (Studies 2 and 3). Methods: Study 1: we will performe a review (overview) of systematic reviews through a search on 5 databases with descriptors related to exposure ("physical inactivity") and outcome (cancer). From eligible systematic reviews, we will assess the quality through AMSTAR and extract data from the included primary studies. We will also evaluate the existence of publication bias using funnel plot and Egger's test. Study 2: we will estimate population attributable fraction for cancers associated with physical inactivity (type of cancers will be based on study 1 findings) in Brazil. Therefore we will use the following equation: PAF = P(RR-1)/RR where P is the prevalence of physical inactivity among cancer cases in Brazil, and RR are the relative risks extracted from systematic reviews. Study 3: we will evaluate the association between physical inactivity and cancer mortality through an ecological study. Physical inactivity data will be extracted from VIGITEL 2006, including work, domestic, transport, and leisure-time domains in persons aged 30 years or more. Assuming 10-year period between exposure and outcome, cancer mortality rates will be calculated to 2016, extracting information from the Brazilian Mortality Information System. (AU)