Age-specific breast cancer risk by body mass index and familial risk: Prospective family study cohort (ProF-SC) 11 Medical and Health Sciences 1112 Oncology and Carcinogenesis 11 Medical and Health Sciences 1117 Public Health and Health Services

John L. Hopper, Gillian S. Dite, Robert J. MacInnis, Yuyan Liao, Nur Zeinomar, Julia A. Knight, Melissa C. Southey, Roger L. Milne, Wendy K. Chung, Graham G. Giles, Jeanine M. Genkinger, Sue Anne McLachlan, Michael L. Friedlander, Antonis C. Antoniou, Prue C. Weideman, Gord Glendon, Stephanie Nesci, Irene L. Andrulis, Saundra S. Buys, Mary B. DalyEsther M. John, Kelly Anne Phillips, Mary Beth Terry

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16 Citations (Scopus)


Background: The association between body mass index (BMI) and risk of breast cancer depends on time of life, but it is unknown whether this association depends on a woman's familial risk. Methods: We conducted a prospective study of a cohort enriched for familial risk consisting of 16,035 women from 6701 families in the Breast Cancer Family Registry and the Kathleen Cunningham Foundation Consortium for Research into Familial Breast Cancer followed for up to 20 years (mean 10.5 years). There were 896 incident breast cancers (mean age at diagnosis 55.7 years). We used Cox regression to model BMI risk associations as a function of menopausal status, age, and underlying familial risk based on pedigree data using the Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA), all measured at baseline. Results: The strength and direction of the BMI risk association depended on baseline menopausal status (P < 0.001); after adjusting for menopausal status, the association did not depend on age at baseline (P = 0.6). In terms of absolute risk, the negative association with BMI for premenopausal women has a much smaller influence than the positive association with BMI for postmenopausal women. Women at higher familial risk have a much larger difference in absolute risk depending on their BMI than women at lower familial risk. Conclusions: The greater a woman's familial risk, the greater the influence of BMI on her absolute postmenopausal breast cancer risk. Given that age-adjusted BMI is correlated across adulthood, maintaining a healthy weight throughout adult life is particularly important for women with a family history of breast cancer.

Original languageEnglish
Article number132
Number of pages11
JournalBreast Cancer Research
Issue number1
Publication statusPublished - 3 Nov 2018


  • Body mass index
  • Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm
  • Breast cancer
  • Familial risk
  • Gene-environment interaction

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