Determinants of breast size in Asian women

Li Yan Lim,Peh Joo Ho,Jingmei Li,Jenny Liu,Mikael Hartman,Min-Han Tan,Wen Yee Chay

doi:10.1038/s41598-018-19437-4

Abstract

Breast size as a risk factor of breast cancer has been studied extensively with inconclusive results. Here we examined the associations between breast size and breast cancer risk factors in 24,353 Asian women aged 50 to 64 years old enrolled in a nationwide mammography screening project conducted between October 1994 and February 1997. Information on demographic and reproductive factors was obtained via a questionnaire. Breast size was ascertained as bust line measured at study recruitment and total breast area measured from a mammogram. The average bust line and total breast area was 91.2 cm and 102.3 cm2, respectively. The two breast measurements were moderately correlated (Spearman correlation coefficient = 0.65). Age, BMI, marital and working status were independently associated with bust line and total breast area. In the multivariable analyses, the most pronounced effects were observed for BMI (24.2 cm difference in bust line and 39.4 cm2 in breast area comparing women with BMI ≥30 kg/m2 to BMI <20 kg/m2). Ethnicity was a positive predictor for total breast area, but not bust line.

Highlights

Breast development occurs during puberty in girls, after which the enlarged breasts are retained throughout adulthood
The mean total breast area, nondense area and dense area captured on mammograms were 102.3 (20.8), 81.3 (24.3) and 21.0 (13.2) cm[2], respectively
Different measurements of breast size, in particular, bust line and total breast area, were only moderately correlated (Spearman correlation coefficient = 0.65). In this large cohort of Singaporean women invited for screening mammography, fatty tissue reflected as nondense area constituted a large proportion of the total breast area captured on mammograms

Summary

Introduction

Breast development occurs during puberty in girls, after which the enlarged breasts are retained throughout adulthood. Breast size in adult women is associated with perceived femininity and is sexually important in many cultures[1,2]. In terms of breast health, breast size has been studied extensively as a risk factor of breast cancer, but the results are inconclusive[7]. A twin study previously estimated the heritability of bra cup size to be 56%8. Several genome-wide association studies have identified common genetic variants associated with breast size[9,10]. We aim to identify non-genetic determinants of breast size using a large cohort of women in Southeast Asia. We examined how the candidate predictors of breast size affects the different tissue components that make up the breast

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