Association between tamoxifen treatment and diabetes

Cancer, 04/16/2012

Current tamoxifen therapy is associated with an increased incidence of diabetes in older breast cancer survivors.


  • This nested case–control study used population–based health databases in Ontario, Canada to identify women older than 65 years with early stage breast cancer between April 1, 1996 and March 31, 2006.
  • Cases were defined as cohort members diagnosed with diabetes during follow–up (March 31, 2008), and each case was age–matched with up to 5 controls who did not develop diabetes.
  • After adjusting for other risk factors, the authors compared the likelihood of diabetes between current tamoxifen users and tamoxifen nonusers, based on prescriptions at diabetes diagnosis.
  • They also compared diabetes risk in current aromatase inhibitor users versus nonusers.


  • Of 14,360 breast cancer survivors identified, mean age 74.9years, 1445 (10%) developed diabetes over a mean follow–up of 5.2years.
  • Current tamoxifen therapy was associated with a significantly higher risk of diabetes compared with no tamoxifen therapy (adjusted odds ratio, 1.24; 95% confidence interval, 1.08–1.42; P=.002).
  • There was no association between aromatase inhibitor therapy and diabetes.

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