e13082 Background: While obesity is considered the risk factors of breast cancer, Asian women are tends to be lower BMI compared with Western populations and there are not much reports that studied association between obesity and risk of breast cancer in Asian women. In this study, we analyzed the associations of breast cancer incidence and body mass index at age 18-20 (BMI 18-20y), BMI at research entry (BMI at entry), change of the BMI from BMI 18-20y to BMI at entry (BMI change), abdominal girth at research entry (AG), HbA1c [N] at research entry (HbA1c). Methods: We used data of the women who had undergone medical check-ups and opportunistic breast cancer screening at least twice at the Center for Preventive Medicine of St. Luke’s International Hospital between April 1, 2005 and March 31, 2014. Statistical analysis was done by using multivariate Cox proportional hazards model to investigate the hazard ratio (HR) at 95% confidence intervals (95% CI). Results: In this 10 year period, 30,109 women (20,043 women were premenopausal and 10,066 women were postmenopausal women) received opportunistic breast cancer screening at least twice. After analysis of 131656.6 person-years follow up during 10 years, 325 initial breast cancer cases were identified 202 cases in premenopausal women, and 123 cases in postmenopausal women. Among postmenopausal women, BMI change and AG were positively associated with breast cancer incidence. Women whose BMI change were major gain group (> +5.0) were significantly likely to develop breast cancer compared with stable group (BMI change were between -2.5 to +2.5) [HR: 1.902 (95% CI = 1.202-3.009)]. Large AG ( > 90cm) was significant risk to develop breast cancer versus less than 70cm [HR: 2.500 (95% CI = 1.091-5.730)]. In the analysis classified BMI18-20y more and less than 20 kg/m2, large BMI18-20y ( > 20 kg/m2) postmenopausal women with high HbA1c ( > 6.5) was more likely to develop breast cancer compared with low HbA1c ( < 5.5) [HR: 3.325(95% CI = 1.307-8.460)]. Conclusions: Increase of BMI after age of 18-20 years and large AG in postmenopausal women have positive association with breast cancer development. High HbA1c women whose BMI18-20y was over 20 kg/m2 are significantly to develop breast cancer.
Recent trends in breast cancer incidence in US white women by county-level urban/rural and poverty status
