Body size over the adult life course and the risk of colorectal cancer among postmenopausal women

Menée aux Etats-Unis auprès de 79 034 femmes ménopausées (durée moyenne de suivi : 15,8 ans), cette étude multicentrique analyse l'association entre plusieurs mesures anthropométriques, des trajectoires de l'indice de masse corporelle entre 18 et 50 ans et le risque de cancer colorectal (1 514 cas)

Résumé en anglais

OBJECTIVE: To assess the associations among several anthropometric measures, as well as BMI trajectories and colorectal cancer (CRC) risk in older women.

DESIGN: Prospective cohort study.

SETTING: Forty clinical centres in the USA.

PARTICIPANTS: Totally, 79 034 postmenopausal women in the Women's Health Initiative Observational Study.

RESULTS: During an average of 15·8 years of follow-up, 1514 CRC cases were ascertained. Five BMI trajectories over 18-50 years of age were identified using growth mixture model. Compared with women who had a normal BMI at age 18, women with obesity at age 18 had a higher risk of CRC (HR 1·58, 95 % CI 1·02, 2·44). Compared with women who kept relatively low normal body size during adulthood, women who progressed from normal to obesity (HR 1·29, 95 % CI 1·09, 1·53) and women who progressed from overweight to obesity (HR 1·37, 95 % CI 1·13, 1·68) had higher CRC risks. A weight gain > 15 kg from age 18 to 50 (HR 1·20, 95 % CI 1·04, 1·40) and baseline waist circumference > 88 cm (HR 1·33, 95 % CI 1·19, 1·49) were associated with higher CRC risks, compared with stable weight and waist circumference ≤ 88 cm, respectively.

CONCLUSION: Women who have a normal weight in early adult life and gain substantial weight later, as well as those who are persistently heavy over adulthood, demonstrated a higher risk of developing CRC. Our study highlights the importance of maintaining a healthy body weight over the life course for reducing the risk of developing CRC in women.