Association of diabetes and diabetes treatment with incidence of breast cancer.
OBJECTIVE
The aim of this study was to evaluate the association of diabetes and diabetes treatment with risk of postmenopausal breast cancer.


METHODS
Histologically confirmed incident cases of postmenopausal breast (N = 916) cancer were recruited from 23 Spanish public hospitals. Population-based controls (N = 1094) were randomly selected from primary care center lists within the catchment areas of the participant hospitals. ORs (95 % CI) were estimated using mixed-effects logistic regression models, using the recruitment center as a random effect term. Breast tumors were classified into hormone receptor positive (ER+ or PR+), HER2+ and triple negative (TN).


RESULTS
Diabetes was not associated with the overall risk of breast cancer (OR 1.09; 95 % CI 0.82-1.45), and it was only linked to the risk of developing TN tumors: Among 91 women with TN tumors, 18.7 % were diabetic, while the corresponding figure among controls was 9.9 % (OR 2.25; 95 % CI 1.22-4.15). Regarding treatment, results showed that insulin use was more prevalent among diabetic cases (2.5 %) as compared to diabetic controls (0.7 %); OR 2.98; 95 % CI 1.26-7.01. They also showed that, among diabetics, the risk of developing HR+/HER2- tumors decreased with longer metformin use (ORper year 0.89; 95 % CI 0.81-0.99; based on 24 cases and 43 controls).


CONCLUSIONS
This study reinforces the need to correctly classify breast cancers when studying their association with diabetes. Given the low survival rates in women diagnosed with TN breast tumors and the potential impact of diabetes control on breast cancer prevention, more studies are needed to better characterize this association.
Environmental and Cancer Epidemiology Unit, National Centre for Epidemiology, Carlos III Institute of Health (Instituto de Salud Carlos III-ISCIII), Avda. Monforte de Lemos, 5, 28029, Madrid, Spain.|Department of Preventive Medicine and Public Health, School of Medicine, Universidad Autónoma de Madrid, Madrid, Spain.|IdiPAZ, Madrid, Spain.|Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.
Esther
E
García-Esquinas
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Unit of Biomarkers and Susceptibility, Catalan Institute of Oncology (ICO-IDIBELL), Barcelona, Spain.
Elisabeth
E
Guinó
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.|IMIM (Hospital del Mar Medical Research Insititute), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.
Gemma
G
Castaño-Vinyals
Environmental and Cancer Epidemiology Unit, National Centre for Epidemiology, Carlos III Institute of Health (Instituto de Salud Carlos III-ISCIII), Avda. Monforte de Lemos, 5, 28029, Madrid, Spain.|Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Institute of Health Research "Puerta de Hierro", IDIPHIM, Madrid, Spain.
Beatriz
B
Pérez-Gómez
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Division of Epidemiology and Computational Biology, School of Medicine, University of Cantabria, IDIVAL, Santander, Spain.
Javier
J
Llorca
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Public Health Divission of Gipuzkoa, BioDonostia Research Institute, San Sebastián, Spain.
Jone M
JM
Altzibar
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Dirección General de Salud Pública, Fundación para el fomento de la investigación sanitaria y biomédica de la Comunidad Valenciana, FISABIO-Salud Pública, Barcelona, Spain.
Rosana
R
Peiró-Pérez
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Grupo de Investigación en Interacción Gen-Ambiente-Salud, Department of Preventive Medicine and Public Health, University of Leon, Leon, Spain.
Vicente
V
Martín
Public Health Institute of Navarra, Pamplona, Spain.|Red de Investigación en Servicios de Salud en Enfermedades Crónicas (REDISSEC), Pamplona, Spain.
Concepción
C
Moreno-Iribas
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Instituto Universitario de Oncología, University of Oviedo, Asturias, Spain.
Adonina
A
Tardón
Hospital Infanta Elena de Huelva, Huelva, Spain.|Centro de Investigación en Salud y Medio Ambiente (CYSMA), Universidad de Huelva, Huelva, Spain.
Francisco Javier
FJ
Caballero
Epidemiology Unit and Girona Cancer Registry (UERCG), Oncology Coordination Plan (PDO), Department of Health, Autonomous Government of Catalonia, Barcelona, Spain.
Montse
M
Puig-Vives
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Public Health Institute of Navarra, Pamplona, Spain.
Marcela
M
Guevara
Grupo de Investigación en Interacción Gen-Ambiente-Salud, Department of Preventive Medicine and Public Health, University of Leon, Leon, Spain.
Tania Fernández
TF
Villa
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Dirección General de Salud Pública, Fundación para el fomento de la investigación sanitaria y biomédica de la Comunidad Valenciana, FISABIO-Salud Pública, Barcelona, Spain.
Dolores
D
Salas
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Public Health Divission of Gipuzkoa, BioDonostia Research Institute, San Sebastián, Spain.
Pilar
P
Amiano
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Division of Epidemiology and Computational Biology, School of Medicine, University of Cantabria, IDIVAL, Santander, Spain.
Trinidad
T
Dierssen-Sotos
Environmental and Cancer Epidemiology Unit, National Centre for Epidemiology, Carlos III Institute of Health (Instituto de Salud Carlos III-ISCIII), Avda. Monforte de Lemos, 5, 28029, Madrid, Spain.|Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Institute of Health Research "Puerta de Hierro", IDIPHIM, Madrid, Spain.
Roberto
R
Pastor-Barriuso
Department of Epidemiology and Evaluation, IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain.
María
M
Sala
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.|IMIM (Hospital del Mar Medical Research Insititute), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.|School of Public Health, Athens, Greece.
Manolis
M
Kogevinas
Environmental and Cancer Epidemiology Unit, National Centre for Epidemiology, Carlos III Institute of Health (Instituto de Salud Carlos III-ISCIII), Avda. Monforte de Lemos, 5, 28029, Madrid, Spain.|Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Institute of Health Research "Puerta de Hierro", IDIPHIM, Madrid, Spain.
Nuria
N
Aragonés
Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain.|Unit of Biomarkers and Susceptibility, Catalan Institute of Oncology (ICO-IDIBELL), Barcelona, Spain.|University of Barcelona, Barcelona, Spain.
Víctor
V
Moreno
Environmental and Cancer Epidemiology Unit, National Centre for Epidemiology, Carlos III Institute of Health (Instituto de Salud Carlos III-ISCIII), Avda. Monforte de Lemos, 5, 28029, Madrid, Spain. mpollan@isciii.es.|Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiología y Salud Pública-CIBERESP), Madrid, Spain. mpollan@isciii.es.|Institute of Health Research "Puerta de Hierro", IDIPHIM, Madrid, Spain. mpollan@isciii.es.
Marina
M
Pollán
D000328:Adult; D001943:Breast Neoplasms / Q000150:complications / Q000453:epidemiology*; D016022:Case-Control Studies; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D017698:Postmenopause; D013030:Spain / Q000453:epidemiology
D008687:Metformin
Breast cancer; Diabetes Mellitus; Insulin; Metformin; Triple-negative breast neoplasms