ASPO Abstracts
Central adiposity and the risk of invasive breast cancer: results from the Nurses' Health Studies
Category: Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2020
Abstract Body:
Purpose: Increased body mass index (BMI), an indicator of general adiposity, is
associated with lower premenopausal breast cancer risk and higher risk of
postmenopausal breast cancer; however, less is known about the association between
central adiposity and breast cancer, particularly for tumor subtypes.
Methods: We prospectively examined the association between self-reported waist
circumference (WC), hip circumference (HC) and waist-to-hip ratio (WHR) and incident
invasive breast cancer in 96,746 women in the Nurses’ Health Studies (NHS, 1986-2016;
NHSII, 1993-2017) by menopausal status. WC and HC were collected twice, 10-12 years
apart. Clinician diagnoses of breast cancer were self-reported and confirmed by medical
record review. Hazard ratios (HR) and 95% confidence intervals (CI) adjusting for breast
cancer risk factors and BMI were estimated by Cox proportional hazard models. Tumor
heterogeneity by hormone receptor and molecular subtypes defined by
immunohistochemical markers was assessed using competing risk analyses.
Results: Over 24-30 years of follow-up, 6,129 incident invasive cases were diagnosed
(1,131 premenopausal cases, 2,089 postmenopausal cases with premenopausal WC,
2,909 postmenopausal cases with postmenopausal WC). At baseline, the mean (SD)
WC, HC and WHR were 79.0 (10.9) cm, 100.9 (10.0) cm and 0.78 (0.07) respectively.
WC and HC were not associated and WHR was positively associated with
premenopausal breast cancer risk (quintile 5 vs. 1: HRQ5vQ1=1.27, 95%CI=1.04-1.54,
p-trend=0.01). Stronger associations were observed for premenopausal estrogen
receptor-negative (ER-)/ progesterone receptor-negative (PR-) and basal-like breast
cancers. Premenopausal WC, HC and WHR were not associated with postmenopausal
breast cancer risk. Postmenopausal WC was positively associated with postmenopausal
breast cancer (HRQ5vQ1=1.38, 95%CI=1.16-1.64, p-trend=0.002); no significant
association was seen for HC or WHR. Associations were stronger for postmenopausal
ER+/PR+ and luminal B breast cancers.
Conclusions: Women with greater central adiposity had higher risk of both
premenopausal and postmenopausal breast cancers, independent of BMI. This suggests
that maintaining a healthy waist circumference may prevent breast cancer even among
premenopausal women.
Keywords: adiposity, breast cancer, waist circumference