Abstract
ObjectivesSeveral studies suggest that overall and central-obesity are associated with increased breast cancer (BC) risk in postmenopausal-women. However, there are no studies investigating changes of central obesity and BC. We report on the association of BC risk with self-reported skirt size (SS; waist-circumference proxy) changes between 20s and postmenopausal-age.DesignProspective cohort-study.SettingUK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) involving the nine trial centres in England.ParticipantsPostmenopausal-women aged >50 with no known history of BC prior to or on the day of completion of the study-entry questionnaire.InterventionsAt recruitment and at study entry, women were asked to complete a questionnaire. Women were followed-up via ‘flagging’ at the NHS Information Centre in England and the Hospital Episode Statistics.Main outcome-measureTime to initial BC diagnosis.ResultsBetween 2 January 2005 and 1 July 2010, 92 834 UKCTOCS participants (median age 64.0) completed the study-entry questionnaire. During median follow-up of 3.19 years (25th–75th centile: 2.46–3.78), 1090 women developed BC. Model adjusted analysis for potential confounders showed body mass index (BMI) at recruitment to UKCTOCS (HR for a 5 unit change=1.076, 95% CI 1.012 to 1.136), current SS at study entry (HR=1.051; 95% CI 1.014 to 1.089) and change in SS per 10 years (CSS) (HR=1.330; 95% CI 1.121 to 1.579) were associated with increased BC risk but not SS at 25 (HR=1.006; 95% CI 0.958 to 1.056). CSS was the most predictive singe adiposity measure and further analysis including both CSS and BMI in the model revealed CSS remained significant (HR=1.266; 95% CI 1.041 to 1.538) but not BMI (HR=1.037; 95% CI 0.970 to 1.109).ConclusionsCSS is associated with BC risk independent of BMI. A unit increase in UK SS (eg, 12–14) every 10-years between 25 and postmenopausal-age is associated with postmenopausal BC risk by 33%. Validation of these results could provide women with a simple and easy to understand message.Trial registration numberISRCTN22488978.
Highlights
Breast cancer is a major global health concern with 1 384 000 women being diagnosed every year.[1]
Model adjusted analysis for potential confounders showed body mass index (BMI) at recruitment to UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) (HR for a 5 unit change=1.076, 95% CI 1.012 to 1.136), current skirt size (SS) at study entry (HR=1.051; 95% CI 1.014 to 1.089) and change in SS per 10 years (CSS) (HR=1.330; 95% CI 1.121 to 1.579) were associated with increased breast cancer (BC) risk but not SS at 25 (HR=1.006; 95% CI 0.958 to 1.056)
change in SS per years (CSS) was the most predictive singe adiposity measure and further analysis including both CSS and BMI in the model revealed CSS remained significant (HR=1.266; 95% CI 1.041 to 1.538) but not BMI (HR=1.037; 95% CI 0.970 to 1.109)
Summary
Breast cancer is a major global health concern with 1 384 000 women being diagnosed every year.[1]. Breast cancer prevention have been accompanied by growing controversies regarding breast cancer screening. Both highlight the need for better risk stratification. During the past few years a growing number of studies have reported on anthropometric factors, on the relationship between breast cancer risk and overall and/or central obesity.[2,3,4]. The oldest and most common measure is body mass index (BMI) which is an empirical proxy for human body fat based on an individual’s weight and height. Central fat is another measure of obesity. It has been suggested that waist circumference independent of BMI, maybe predictive of increased health risk.[6]
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