Height and Body Mass Index as Modifiers of Breast Cancer Risk in BRCA1/2 Mutation Carriers: A Mendelian Randomization Study

Frank Qian, Shengfeng Wang, Jonathan Mitchell, Lesley McGuffog, Daniel Barrowdale, Goska Leslie, Jan C. Oosterwijk, Wendy K. Chung, D. Gareth Evans, Christoph Engel, Karin Kast, Cora M. Aalfs, Muriel A. Adank, Julian Adlard, Bjarni A. Agnarsson, Kristiina Aittomäki, Elisa Alducci, Irene L. Andrulis, Banu K. Arun, Margreet G. E. M. AusemsJacopo Azzollini, Emmanuelle Barouk-Simonet, Julian Barwell, Muriel Belotti, Javier Benitez, Andreas Berger, Ake Borg, Angela R. Bradbury, Joan Brunet, Saundra S. Buys, Trinidad Caldes, Maria A. Caligo, Ian Campbell, Sandrine M. Caputo, Jocelyne Chiquette, Kathleen B. M. Claes, J. Margriet Collée, Fergus J. Couch, Isabelle Coupier, Mary B. Daly, Rosemarie Davidson, Orland Diez, Susan M. Domchek, Alan Donaldson, Cecilia M. Dorfling, Ros Eeles, Lidia Feliubadaló, Lenka Foretova, Hanne E. J. Meijers-Heijboer, Klaartje van Engelen, HEBON, EMBRACE, GEMO Study Collaborators, Mark H. Greene, Antonis C. Antoniou, David E. Goldgar, Olufunmilayo I. Olopade, Timothy R. Rebbeck, Dezheng Huo

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BACKGROUND: BRCA1/2 mutations confer high lifetime risk of breast cancer, although other factors may modify this risk. Whether height or body mass index (BMI) modifies breast cancer risk in BRCA1/2 mutation carriers remains unclear. METHODS: We used Mendelian randomization approaches to evaluate the association of height and BMI on breast cancer risk, using data from the Consortium of Investigators of Modifiers of BRCA1/2 with 14 676 BRCA1 and 7912 BRCA2 mutation carriers, including 11 451 cases of breast cancer. We created a height genetic score using 586 height-associated variants and a BMI genetic score using 93 BMI-associated variants. We examined both observed and genetically determined height and BMI with breast cancer risk using weighted Cox models. All statistical tests were two-sided. RESULTS: Observed height was positively associated with breast cancer risk (HR = 1.09 per 10 cm increase, 95% confidence interval [CI] = 1.0 to 1.17; P = 1.17). Height genetic score was positively associated with breast cancer, although this was not statistically significant (per 10 cm increase in genetically predicted height, HR = 1.04, 95% CI = 0.93 to 1.17; P = .47). Observed BMI was inversely associated with breast cancer risk (per 5 kg/m2 increase, HR = 0.94, 95% CI = 0.90 to 0.98; P = .007). BMI genetic score was also inversely associated with breast cancer risk (per 5 kg/m2 increase in genetically predicted BMI, HR = 0.87, 95% CI = 0.76 to 0.98; P = .02). BMI was primarily associated with premenopausal breast cancer. CONCLUSION: Height is associated with overall breast cancer and BMI is associated with premenopausal breast cancer in BRCA1/2 mutation carriers. Incorporating height and BMI, particularly genetic score, into risk assessment may improve cancer management.
Original languageEnglish
Pages (from-to)350-364
Number of pages15
JournalJournal of the National Cancer Institute
Issue number4
Early online date12 Oct 2018
Publication statusPublished - 1 Jan 2019

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