Body shape trajectories and risk of breast cancer: results from the SUN (

Abstract

Objective: The aim of this study was to assess body shape trajectories in childhood and midlife in relation to subsequent risk of breast cancer (BC) in a Mediterranean cohort.

Design: The “Seguimiento Universidad de Navarra” (SUN) Project is a dynamic prospective cohort study of university graduates initiated in 1999. With a group-based modelling approach, we assessed body shape trajectories from age 5 to 40 years. Multivariable Cox regression models were used to estimate the hazard ratio (HR) for BC after the age of 40 years according to the body shape trajectory.

Setting: City of Pamplona, in the North of Spain.

Participants: 6498 women with a mean age of 40 years (sd 9).

Results: We identified four distinct body shape trajectories ("childhood lean-midlife increase" (19·9 %), "childhood medium-midlife stable” (53 %), "childhood heavy-midlife stable" (21 %) and "childhood heavy-midlife increase" (6·1 %)). Among 54 978 women-years of follow-up, we confirmed eighty-two incident cases of BC. Women in the "childhood lean-midlife increase" group showed a higher risk of BC (HR = 1·84, 95 % CI 1·11, 3·04) compared with women in the "childhood medium-midlife stable" category. This association was stronger for postmenopausal BC (HR = 2·42, 95 % CI 1·07, 5·48).

Conclusions: Our results suggest a role for lifetime adiposity in breast carcinogenesis.