title: Type II Diabetes, Obesity, and Breast Cancer Risk: The Multiethnic Cohort.
abstract: Background:Obesity has been more consistently associated with breast cancer than type II diabetes. This analysis examined the combination of the two factors in the Multiethnic Cohort (MEC).Methods:Women ages 45-75 years entered the MEC in 1993-1996 by completing a questionnaire. Type II diabetes status was self-reported at baseline, two follow-up questionnaires, and confirmed by administrative data. Cancers were identified from tumor registries and deaths through vital records until 2010. Cox regression was applied to estimate HRs and 95% confidence intervals (CI) for BMI and type II diabetes status alone and in combination.Results:Among 103,721 (25,146 white, 20,255 African American, 7,681 Native Hawaiian, 28,012 Japanese American, 22,627 Latina) women with 14,558 type II diabetes cases, 6,692 women developed breast cancer during 14.8 ± 4.1 years of follow-up. Type II diabetes was significantly associated with breast cancer risk (HR, 1.15; 95% CI, 1.07-1.23), but including body mass index (BMI) lowered the HR to 1.08 (95% CI, 1.00-1.16). Ethnic-specific BMI-adjusted models showed elevated risks for type II diabetes in Latinas only (HR, 1.30; 95% CI, 1.11-1.52). In contrast, obesity predicted statistically significant 21%-46% higher risks, after type II diabetes adjustment, in all ethnic groups except Latinas (HR, 1.17; 95% CI, 0.99-1.38).Conclusions:As reported previously, inclusion of BMI weakened the association of type II diabetes with breast cancer. Type II diabetes status, but not BMI, was primarily associated with higher breast cancer risk in Latinas.Impact:The role of obesity and type II diabetes in breast cancer etiology may differ by ethnicity suggesting metabolic differences related to obesity.Cancer Epidemiol Biomarkers Prev; 26(6); 854-61. ©2017 AACR.
authors.affiliation: Epidemiology Program, University of Hawaii Cancer Center, Honolulu, Hawaii. gertraud@cc.hawaii.edu.
authors.forename: Gertraud
authors.initials: G
authors.lastname: Maskarinec
authors.affiliation: Epidemiology Program, University of Hawaii Cancer Center, Honolulu, Hawaii.
authors.forename: Simone
authors.initials: S
authors.lastname: Jacobs
authors.affiliation: Epidemiology Program, University of Hawaii Cancer Center, Honolulu, Hawaii.
authors.forename: Song-Yi
authors.initials: SY
authors.lastname: Park
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Haiman
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California.
authors.forename: Veronica W
authors.initials: VW
authors.lastname: Setiawan
authors.affiliation: Epidemiology Program, University of Hawaii Cancer Center, Honolulu, Hawaii.
authors.forename: Lynne R
authors.initials: LR
authors.lastname: Wilkens
authors.affiliation: Epidemiology Program, University of Hawaii Cancer Center, Honolulu, Hawaii.
authors.forename: Loïc
authors.initials: L
authors.lastname: Le Marchand
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000208:ethnology* / Q000209:etiology* / Q000473:pathology; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D012307:Risk Factors