Cumulative exposure to premenopausal obesity and risk of postmenopausal cancer: A population-based study in Icelandic women
Menée en Islande auprès d'une cohorte de 88 809 femmes (durée moyenne de suivi : 17 ans), cette étude analyse l'association entre les mesures combinées de la durée et du niveau de l'obésité avant la ménopause et le risque de cancer colorectal (987 cas), de cancer du sein (3 016 cas) ou de l'endomètre (410 cas) après la ménopause
Obesity, often assessed at one point in time, is an established risk factor of several types of cancer, however, associations with cumulative exposure to obesity across the life course are not well understood. We investigated the relationship between combined measures of duration and intensity of premenopausal overweight and obesity and the incidence of postmenopausal breast, endometrial, and colorectal cancers in Icelandic women. Body Mass Index (BMI) trajectories between ages 20 and 50 of 88,809 women from the Cancer Detection Clinic Cohort were predicted using growth curve models. Indicators of overweight and obesity duration and intensity were computed and their association with risk of postmenopausal breast, endometrial, and colorectal cancers was examined using multivariate Cox models for subjects followed-up beyond the age of 50 (n=67,488). During a mean follow-up of 17 years, incident events of 3,016 postmenopausal breast, 410 endometrial, and 987 colorectal cancers were ascertained. Each 0.1 kg/m2 per year increase in BMI between ages 20 and 50 was positively associated with risks of postmenopausal breast, endometrium, and colorectal cancers with hazard ratios equal to 1.09 (95% Confidence Interval (CI):1.04-1.13), 1.31 (95%CI: 1.18-1.44), and 1.10 (95%CI: 1.00-1.21), respectively. Compared to women who were never obese, cumulative BMI×years of obesity were linearly positively associated with risk of endometrial cancer, whereas the association with breast cancer was initially positive, but levelled off with increasing cumulative BMI×years. Cumulative exposure to obesity may provide additional insights into the etiology of cancer and should be considered in future studies that assess obesity-cancer relationships. This article is protected by copyright. All rights reserved.