title: Ethnic differences in mammographic densities: an Asian cross-sectional study.
abstract: BACKGROUND
  Mammographic density is a strong risk factor for breast cancer and is highly variable, but, to date, few studies have examined density in Asian women, particularly those in low and middle-income Asian countries where genetic and lifestyle determinants may be significantly different.
  
  
  METHODS
  A total of 1,240 women who attended an opportunistic mammogram screening programme were eligible for analysis. Mammographic density was estimated using a fully-automated thresholding method and differences across ethnic groups were examined using linear regression in 205 randomly selected Chinese women, 138 Malay and 199 Indian women.
  
  
  RESULTS
  Percent density was significantly higher in Chinese women (28.5%; 95% CI 27.0%, 30.0%) compared to Malay (24.2%; 95% CI 22.5%, 26.0%) and Indian (24.3%; 95% CI 22.8%, 25.7%) women (p<0.001), after adjustment for age, BMI, menopausal status, parity and age at first full term pregnancy. Correspondingly, adjusted nondense area was significantly lower in Chinese (72.2cm2; 95% CI 67.9cm2, 76.5cm2) women compared to Malay (92.1cm2; 95% CI 86.9cm2, 97.2cm2) and Indian (97.7cm2; 95% CI 93.4cm2, 101.9cm2) women (p<0.001), but dense area did not differ across the three ethnic groups.
  
  
  CONCLUSIONS
  Our study shows that higher percent density and lower nondense area reflect the higher incidence of breast cancer in Chinese compared to Malay and Indian women in Malaysia. Known lifestyle determinants of mammographic density do not fully account for the ethnic variations observed in mammographic density in this Asian cohort.
authors: Cancer Research Initiatives Foundation, Sime Darby Medical Centre, 1 Jalan SS12/1A, Subang Jaya, 47500 Selangor, Malaysia; Breast Cancer Research Unit, University Malaya Cancer Research Institute, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
authors: Shivaani
authors: S
authors: Mariapun
authors: Human Genetics, Genome Institute of Singapore, Singapore 138672, Singapore.
authors: Jingmei
authors: J
authors: Li
authors: Sime Darby Medical Centre, 1 Jalan SS12/1A, Subang Jaya, 47500 Selangor, Malaysia.
authors: Cheng Har
authors: CH
authors: Yip
authors: Breast Cancer Research Unit, University Malaya Cancer Research Institute, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
authors: Nur Aishah Mohd
authors: NA
authors: Taib
authors: Cancer Research Initiatives Foundation, Sime Darby Medical Centre, 1 Jalan SS12/1A, Subang Jaya, 47500 Selangor, Malaysia; Breast Cancer Research Unit, University Malaya Cancer Research Institute, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
authors: Soo-Hwang
authors: SH
authors: Teo
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D044466:Asian People / Q000208:ethnology* / Q000523:psychology; D001294:Attitude to Health / Q000208:ethnology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008296:Malaysia / Q000208:ethnology; D008327:Mammography; D008875:Middle Aged; D011247:Pregnancy; D012846:Singapore / Q000208:ethnology