Andrew Renehan

Ph.D.,FRCS

University of Manchester

Professor of Cancer Studies and Surgery

PLCO (Learn more about this study)

PLCO-752

Mar 30, 2021

Adolescent and adulthood BMI And Cancer risk using obese-year metrics: the ABACus 2 project

Body fatness, classed under the World Health Organisation (WHO) as a Body Mass Index (BMI) of 25.0 kg/m2 or higher, is the second largest preventable cause of cancer. A ‘once-only’ (cross-sectional) measure of BMI at the study entry is generally used to determine an individual’s body fatness. This has limited use in cancer prevention as it fails to capture prior exposure of excess body fatness such as the prior intensity and duration of exposure to body fatness. Previously, the ABACus project developed latent class trajectory models to capture life-course exposure to body fatness, which generated hypotheses of weight changes in adulthood that were gender specific and generated age-specific weight changes on a population level. ABACus2 is an extension of the previously approved ABACus project.

In ABACus 2, we will focus on establishing how the association between body fatness and cancer changes throughout the life-course, thereby identifying whether targeted intervention through easy modifications at relevant and critical time points in the life course can minimise the body fatness related cancer risk. Using methodology comparable to tobacco smoking pack-years, we will determine individual obese-year metrics that takes into account both the intensity and the duration of body fatness and relate this to cancer risk. Landmark analysis and other longitudinal methodologies will be used to understand the critical age periods across the life-course. In epidemiology literature, primary focus in most studies is on body fatness exposure in adulthood. Limited research is available on body fatness exposure in childhood possibly due to the lack of availability of repeated BMI measures due to the need for repeated consent. With an increasing prevalence of body fatness in children alongside study observations on the contributions to the body fatness related cancer risk (3,4), it is fundamental to research body fatness exposure in childhood. To understand exposure to body fatness earlier on in the life-course, we will use novel methods to backward extrapolate body fatness exposure using child growth curve algorithms. More specific quantification of the exposure to body fatness and understanding of critical age periods, where the obesity associated cancer risk is stronger, will better inform of underlying mechanisms associated with the obesity-cancer link. The ABACus 2 project will help optimise targeted prevention strategies, establish changes in public health policy and enable translation to clinical practice.