title: The association between diabetes and breast cancer stage at diagnosis: a population-based study.
abstract: Women with diabetes have higher breast cancer incidence and mortality. The purpose of this study was to examine the impact of diabetes on stage at breast cancer diagnosis, as a possible reason for their higher mortality. Using population-based health databases from Ontario, Canada, this retrospective cohort study examined stage at diagnosis (II, III, or IV vs I) among women aged 20-105 years who were newly diagnosed with invasive breast cancer between 2007 and 2012. We compared those with diabetes to those without diabetes. Diabetes was defined based on medical records using a validated algorithm. Among 38,407 women with breast cancer, 6115 (15.9 %) women had diabetes. Breast cancer patients with diabetes were significantly more likely to present with advanced-stage breast cancer than those without diabetes. After adjustment for mammograms and other covariates, diabetes was associated with a significantly increased risk of Stage II [adjusted odds ratio (aOR) 1.14, 95 % confidence interval (CI) 1.07, 1.22], Stage III (aOR 1.21, 95 % CI 1.11, 1.33), and Stage IV (aOR 1.16, 95 % CI 1.01, 1.33) versus Stage I breast cancer. Women with diabetes had a higher risk of lymph node metastases (aOR 1.16, 95 % CI 1.06, 1.27) and tumors with size over 2 cm (aOR 1.16, 95 % CI 1.06, 1.28). Diabetes was associated with more advanced-stage breast cancer, even after accounting for differences in screening mammogram use and other factors. Our findings suggest that diabetes may predispose to more aggressive breast cancer, which may be a contributor to their higher cancer mortality.
authors.affiliation: Women's College Research Institute, Women's College Hospital, 790 Bay St, Room 741, Toronto, ON, M5G 1N8, Canada, lorraine.lipscombe@wchospital.ca.
authors.forename: Lorraine L
authors.initials: LL
authors.lastname: Lipscombe
authors.forename: Hadas D
authors.initials: HD
authors.lastname: Fischer
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.forename: Longdi
authors.initials: L
authors.lastname: Fu
authors.forename: R Liisa
authors.initials: RL
authors.lastname: Jaakkimainen
authors.forename: Ophira
authors.initials: O
authors.lastname: Ginsburg
authors.forename: Paula A
authors.initials: PA
authors.lastname: Rochon
authors.forename: Steven
authors.initials: S
authors.lastname: Narod
authors.forename: Lawrence
authors.initials: L
authors.lastname: Paszat
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000209:etiology* / Q000473:pathology*; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D009864:Ontario / Q000453:epidemiology; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult