Diabetes mellitus and breast cancer: a retrospective population-based cohort study
- 310 Downloads
Evidence suggests that women with type 2 diabetes may be at increased risk of breast cancer, possibly due to chronic exposure to insulin resistance and/or hyperinsulinemia. The purpose of this study was to compare the incidence of breast cancer in postmenopausal women with and without diabetes.
Using population-based validated health databases from Ontario, Canada, this retrospective cohort study compared breast cancer incidence between women, aged 55–79 years, with newly diagnosed diabetes (n=73,796) to women without diabetes (n=391,714).
Women with diabetes were slightly older, were more likely to reside in a lower income neighborhood, had greater comorbidity, and had more annual physician visits than women without diabetes. After 2.2 million person-years of follow-up from 1994 to 2002, breast cancer incidence was 2.97/1000 person-years in the diabetes group and 2.75/1000 person-years in the non-diabetes group. After adjustment for age and income, there was a significant increase in breast cancer among women with diabetes (hazard ratio, HR, 1.08, 95% confidence interval, CI, 1.01–1.16, p=0.021).
This study found a small but significant increase in incident breast cancer in a predominantly postmenopausal population of women with diabetes, when compared to women without diabetes. These results support the possibility that insulin resistance or some other aspect of type 2 diabetes may promote breast cancer, and may further direct treatment and prevention strategies.
Keywordsbreast cancer cohort study diabetes epidemiology insulin resistance risk
The authors gratefully acknowledge the assistance of Nadia Gunraj in data collection. L. Lipscombe is supported by the Canadian Diabetes Association’s Marsha Howarth–Schwarz Postgraduate Fellowship. J. McLaughlin is supported as an Investigator by the Canadian Institutes of Health Research. B. Zinman holds the Sam and Judy Pencer Family Chair in Diabetes Research at Mount Sinai Hospital, University of Toronto. P. Goodwin holds the Marvelle Koffler Chair in Breast Research at Mount Sinai Hospital, University of Toronto.
- 1.American Cancer Society. Cancer facts and figures, 2003–2004. 2005: American Cancer Society, 2004Google Scholar
- 5.Rossouw JE, Anderson GL, Prentice RL, LaCroix AZ, Kooperberg C, Stefanick ML, Jackson RD, Beresford SA, Howard BV, Johnson KC, Kotchen JM, Ockene J Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the women’s health initiative randomized controlled trial JAMA 288: 321–333, 2002PubMedCrossRefGoogle Scholar
- 35.Hux JE, Tang M 2003 Chapter 1: Patterns of prevalence and incidence of daibetes In: JE Hux, Booth G, Laupacis A (eds) Diabetes in Ontario: An ICES Practice Atlas Toronto, Canada Institute for Clinical Evaluative SciencesGoogle Scholar
- 45.McLaughin JR, Sloan MR, Janovjak DP: Cancer survival in Ontario. The Ontario Cancer Treatment and Research Foundation: 1–9, 1995Google Scholar
- 47.Weiner JP, Abrams C: ACG Software Documentation/Users Manual, Version 5.0. Johns Hopkins University, 2001Google Scholar
- 48.Shah BR, Mamdani M, Kopp A 2003 Chapter 3: Drug use in older people with diabetes In: JE Hux, Booth G, Laupacis A (eds) Diabetes in Ontario: An ICES Practice Atlas Toronto, Canada Institute for Clinical Evaluative SciencesGoogle Scholar