br b Department of Documentation

b Department of Documentation & Quality, Danish Cancer Society, Copenhagen, Denmark
c Department of Cancer Prevention and Information, Danish Cancer Society, Copenhagen, Denmark
d Division of Risk Assessment and Nutrition, National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
e Finnish Cancer Registry - Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland
f Faculty of Social Sciences, University of Tampere, Tampere, Finland
g Department of Clinical Neuroscience, Division of Insurance Medicine, Karolinska Institutet, Stockholm, Sweden
h Icelandic Cancer Registry, Icelandic Cancer Society, Reykjavik, Iceland
i Faculty of Medicine, University of Iceland, Reykjavik, Iceland
j Department of Research, Cancer Registry of Norway - Institute of Population-Based Cancer Research, Oslo, Norway
k Genetic Epidemiology Group, Folkha¨lsan Research Center, Faculty of Medicine, Helsinki University, Helsinki, Finland
l Department of Community Medicine, University of Tromsø, The Arctic University of Norway, Tromsø, Norway
m Danish Cancer Society, Copenhagen, Denmark
KEYWORDS
Moderate and
vigorous physical
activity;
Cancer;
Prevention;
Population
attributable fraction;
Abstract Background: Physical activity has been shown to reduce the risk of colon, endome-trial and postmenopausal breast cancer. The aim of this study was to quantify the proportion of the cancer burden in the Nordic countries linked to insufficient levels of leisure time phys-ical activity and estimate the potential for cancer prevention for these three sites by increasing physical activity levels.
Methods: Using the Prevent macrosimulation model, the number of cancer cases in the Nordic countries over a 30-year Okadaic acid (2016e2045) was modelled, under different scenarios of increasing physical activity levels in the population, and compared with the projected number
* Corresponding author: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77 Stockholm, Sweden.
E-mail address: therese.m-l.andersson@ki.se (T.M.-L. Andersson).
Potential impact
fraction;
Nordic countries;
Prevent
macrosimulation
model;
Breast cancer;
Colon cancer;
Endometrial cancer 
of cases if constant physical activity prevailed. Physical activity (moderate and vigorous) was categorised according to metabolic equivalents (MET) hours in groups with sufficient physical activity (15þ MET-hours/week), low deficit (9 to <15 MET-hours/week), medium deficit (3 to <9 MET-hours/week) and high deficit (<3 MET-hours/week).
Results: If no one had insufficient levels of physical activity, about 11,000 colon, endometrial and postmenopausal breast cancer cases could be avoided in the Nordic countries in a 30-year period, which is 1% of the expected cases for the three cancer types. With a 50% reduction in all deficit groups by 2025 or a 100% reduction in the group of high deficit, approximately 0.5% of the expected cases for the three cancer types could be avoided. The number and percentage of avoidable cases was highest for colon cancer.
Conclusion: 11,000 cancer cases could be avoided in the Nordic countries in a 30-year period, if deficit in physical activity was eliminated.
ª 2019 Elsevier Ltd. All rights reserved.
1. Introduction
Strong evidence shows that physical activity of both moderate and vigorous intensity has a direct protective effect against cancer of the colon, breast (postmeno-pause) and endometrium [1e4] and potentially decreases the risk of more cancer sites [5,6]. Despite the fact that physical activity decreases the risk of several diseases, a fourth of the adult population worldwide does not meet the minimum guidelines [7]. From 2001 to 2016, the prevalence of physical inactivity increased almost six percentage points in high-income Western countries (including Denmark, Sweden, Finland and Norway) resulting in 36,8% of the population with an insufficient physical activity level in 2016 [7]. It is therefore relevant to estimate the impact of an increase in the level of physical activity on cancer incidence. This is, to our knowledge, the first study aimed at estimating the total number and proportion of preventable cases for breast, colon and endometrial cancers in the Nordic countries according to different scenarios of increased levels of physical activity.