Anthropometric factors, physical activity, and breast cancer risk in relation to hormone receptor and menopausal status in Japanese women: a case–control study
Menée au Japon auprès de 1 017 cas et 2 902 témoins, cette étude analyse l'association entre des facteurs anthropométriques, une activité physique et le risque de cancer du sein, en fonction du statut des récepteurs hormonaux et du statut ménopausique
Purpose : The associations between anthropometric factors, physical activity (PA), and breast cancer risk in terms of estrogen-receptor/progesterone-receptor (ER/PgR) status have been unclear in Japanese women. This case–control study was designed to evaluate these associations. Methods : From among female patients aged 30 years and over admitted to a single hospital in Japan between 1997 and 2009, 1,017 breast cancer cases (538ER+/PgR+, 125ER+/PgR−, 23 ER−/PgR+, 249 ER−/PgR−, and 82 missing) and 2,902 controls were selected. Height, weight, body mass index (BMI) (kg/m2), and time spent exercising (hours/week) were assessed using a self-administered questionnaire. Polytomous logistic regression analysis and tests for heterogeneity across ER+/PgR+ and ER−/PgR− were conducted. Results : Higher BMI was associated with a higher risk of ER+/PgR+ cancer among women overall [odds ratio (OR) = 2.41, 95 % confidence interval (CI) 1.37–4.23 for BMI ≥30.0; P trend = 0.0001] and postmenopausal women (OR = 6.24, 95 % CI 2.68–14.53 for BMI ≥30.0; P trend < 0.0001). A longer time spent exercising (more than 5 h/week) showed a decreased risk for any type of breast cancer among overall and pre- and postmenopausal women, although this did not reach statistical significance. Height was not associated with any risk. Conclusions : Higher BMI is associated with an increased risk of ER+/PgR+ cancer among women overall and postmenopausal women. PA might be associated with a decreased