br Introduction br Lack of physical activity is
Lack of physical activity is a known risk factor for various co-mor-bidities, including cancers of the colon, postmenopausal breast and corpus uteri [1–7]. Physical activity is defined as any movement of the skeletal muscles that increases 2097381-85-4 expenditure above the resting energy expenditure, including all movements performed in the daily life. Physical activities are furthermore classified into groups according to their light, moderate or vigorous intensity. While insufficient phy-sical activity refers to the lack of moderate-to-vigorous physical ac-tivity, physical inactivity relates to an excess of light activities. Glob-ally, the prevalence of insufficient physical activity varies substantially
across world regions, but has increased markedly over the past decades [8,9].
The World Health Organization  recommends a minimum of
30 min of moderate-to-vigorous physical activity at least five days a week (i.e., accumulating 150 min per week) that can be sequenced in periods of at least 10 min. In France, the most recent guidelines for optimal health from the framework of the National Health and Nutri-tion Program  recommend at least 30 min per day of moderate-to-vigorous physical activity (equivalent to 210 min per week of brisk walking). In 2016, an estimated 29.3% of the French adult population was considered insufficiently physically active (defined as less than 150 min of moderate-to-vigorous, or 75 min of vigorous-intensity
Corresponding author at: Section of Cancer Surveillance, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, France. E-mail address: [email protected] (I. Soerjomataram).
1877-7821/ © 2019 International Agency for Research on Cancer. Published by Elsevier Ltd. All rights reserved.
Estimated proportion (%) of sufficient and insufficient physical activity relatively to the reference level of 21 MET-hours per week (corresponding to 0.5 h × 7
Deficit in MET-hrs Men
physical activity per week, or any equivalent combination of the two), which is slightly above the global average (27.5%) . When the French guidelines are used, less than half of French adults attain the recommended level of physical activity . Increasing physical ac-tivity levels in the French population may thus have a beneficial impact on the future cancer burden, especially since the affected sites such as colon and breast cancers are the most commonly diagnosed cancers in France. In this study, we aimed to estimate the proportion and number of cancer cases that were attributable to insufficient physical activity in France in 2015 by cancer site and sex.
2.1. Prevalence of insufficient physical activity
Data on physical activity levels in the French population, by sex and age group (20–29, 30–39, 40–49, 50–59, 60–69, 70+ years) were ob-tained from self-reported assessments of the National Nutrition and Health Survey (Etude nationale nutrition santé, ENNS) in 2006 (Table 1) . ENNS is a national cross-sectional survey with a multi-stage sampling design conducted between February 2006 and March 2007 by the French Institute for Health Surveillance (formerly Institut National de Veille Sanitaire, now Santé Public France) among 3115 adults aged 18–74 years and residing in France. Detailed sampling strategy has been reported elsewhere . In brief, three-stage sampling was per-formed: firstly, 190 geographic areas were randomly selected throughout France followed by a random selection of dwellings based on randomly generated phone lists and the selection of eligible subjects to be included in the study. ENNS reported the prevalence estimates of different types of physical activity according to their intensity measured in metabolic equivalents (METs) in 2971 individuals: fast walking or other moderate physical activity (3–6 METs) and vigorous physical activity (> 6 METs) , derived from the International Physical Ac-tivity Questionnaire (IPAQ, short version) administered during face-to-face interviews . One MET represents resting energy expenditure, which equals about 3.5 mL O2/kg when measured in terms of oxygen consumption or expenditure of 4.184 kJ per hour. The intensity of all types of physical activity is generally expressed as multiples of the resting energy expenditure (1 MET) using a standard reference of en-ergy costs of activities.
In the main analysis, we estimated the proportion of cancer cases attributable to insufficient physical activity. Here, sufficient physical activity was defined according to the French recommendations corre-sponding to a daily minimum of 30 min of moderate-to-vigorous phy-sical activity. We assumed that moderate-to-vigorous physical activities had an average intensity of 6 METs that represent the midpoint of moderate (3–6 METs) and vigorous (> 6 METs) physical activity [15,16]. Assuming that physical activity of at least moderate intensity was performed 30 min every day for seven days a week, the reference