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


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Nadin Hawwash, Glen Martin, Matthew Sperrin, Andrew Renehan

Abstract

Background

Body fatness, commonly approximated as a Body Mass Index (BMI) of 25.0 kg/m2 or higher, is the second largest preventable cause of cancer. Within the Manchester NIHR BRC Cancer Prevention Theme, there is a research programme evaluating life-course excess weight exposure and cancer risk, the ABACus project. We previously developed latent class trajectory models, generating hypotheses of gender-specific weight changes through adulthood, but these models have limited generalizability. In this unique PhD within the MB programme (CRUK ARTIC award) – starting October 2020 - we will use new methodologies to determine individual obese-year metrics. This methodology is comparable to pack-years in relation to tobacco smoking.

Method

Using the ABACus consortium consisting of four cohorts, we will determine individual obese-year metrics and to assess for critical age periods during an individual’s lifetime. Through four workstreams, we will do the following:

1: Use the repeated BMI measurements from the ABACus consortium to determine individual obese-year metrics, namely, level of obesity, duration of obesity, obese-years and cumulative total obese-years, relate to cancer risk, and compare with once-only BMI measures;

2: From 1 above, explore the impact of effect modifiers such as gender, smoking and HRT use. (This modelling is important for developing personalised prevention strategies);

3: Use landmark analysis approaches to fit separate models to assess for ‘critical age periods’ – for example, early adulthood or peri-menopausal;

4: As an additional novel dimension, explore backward estimations of cumulative excess weight during adolescence based on known attained heights and age of menarche.

Results


Conclusion

Our project will quantify the cumulative exposure of obesity, thereby providing a tailored and specific indicator of the cancer risk throughout an individual’s lifetime. ABACus 2 will identify critical age periods whereby exposure to obesity poses a greater cancer risk to help design, implement and optimise prevention strategies and establish changes in public health policy.

Impact statement

ABACus 2 aims to better quantify exposure to obesity and provide a greater understanding regarding the obesity-related cancer risk in an individuals’ lifetime to optimise prevention strategies and establish changes in public health policy.