Diabetes mellitus and breast cancer: a retrospective population-based cohort study
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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
- 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