Lifetime BMI trajectory classes and obesity-related cancer risk in a US retrospective cohort study
Session type: Poster / e-Poster / Silent Theatre session
Theme: Epidemiology and prevention
Body mass index (BMI) is positively associated with increased risk of several adult cancers. There are now ten established obesity-related (OR) cancers listed by the World Cancer Research Fund . The development of many cancers is over years, even decades. It is important to study the association of overweight and obesity measured over a lifetime with cancer incidence.
Latent class longitudinal models are used to cluster BMI trajectories to give a simplified representation of complex longitudinal structures in heterogeneous populations. We derive 5 gender-specific model-based trajectory classes from a US cohort of over 300,000 individuals with 4 recalled BMI meausrements and infer associated obesity-related cancer risk allowing us to model heterogeneity through latent classes of trajectories.
The majority of the male study population fall into the lean-moderate increase (reference: 68%) and medium-marked increase (25%) where we observe a significant increase in OR cancer risk HR=1.24 [95% CI 1.16,1.32] and higher increases for the lean-marked increase (4%) and heavy-increase (3%) classes with HR=1.50 [95% CI 1.32, 1.70] and HR=1.53 [95% CI 1.32, 1.79] respectively. Most women fall into three classes; lean-moderate increase (41%), lean-stable (reference: 33%) and lean-marked increase (21%) with moderate increases in OR cancer risk; lean-marked increase HR=1.17 [95% CI 1.11,1.24] and HR=1.07 [95% CI 1.01, 1.12] for lean-moderate increase category. We observe null effects of BMI trajectory class for the non-obesity-related cancers in both genders.
BMI trajectories with marked and heavy increases over an individuals lifetime are associated with increase risk of obesity-related cancers which are gender and cancer subtype specific. The lean-stable and lean-moderate increase classes have the lowest obesity-related cancer risk indicating many new obesity-related cancers are avoidable.
 World Cancer Research Fund / American Institute for Cancer Research, “Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective.,” Washington DC, 2007.