Authors: Lorraine L Lipscombe Pamela J Goodwin Bernard Zinman John R McLaughlin Janet E Hux
Publish Date: 2007/07/21
Volume: 109, Issue: 2, Pages: 389-395
Abstract
Purpose It has been suggested that type 2 diabetes may affect breast cancer prognosis possibly due to increased diabetesrelated comorbidity or direct effects of insulin resistance and/or hyperinsulinemia The purpose of this study was to examine the impact of diabetes on survival following breast cancer Methods Using populationbased health databases from Ontario Canada this retrospective cohort study compared deaths between women with breast cancer aged 55–79 years with diabetes and without diabetes Women were followed for all cause mortality from breast cancer diagnosis until March 31st 2006 Results Of the 6107 women with breast cancer 1011 had diabetes and 5096 did not have diabetes Women with diabetes were slightly older were more likely to reside in a lower income neighborhood and had greater comorbidity compared to women without diabetes After a mean followup of 50 years and adjustment for age prior mammograms and other covariates mortality following breast cancer was significantly higher among women with versus without diabetes hazard ratio HR 139 95 confidence interval CI 122–159 P 00001 The effect of diabetes on mortality was comparable to that seen in women with diabetes without breast cancer over a 7year followup Conclusion This study found that diabetes was associated with a close to 40 increase in mortality within the first 5 years following breast cancer which was similar to that seen in women with diabetes without breast cancer These findings suggest that early survival following breast cancer is reduced in women with diabetes possibly due to diabetesrelated causesThe Institute for Clinical Evaluative Sciences is funded by the Ontario Ministry of Health and Longterm Care The opinions results and conclusions are those of the authors and no endorsement by the Ministry of Health and LongTerm Care or by the Institute for Clinical Evaluative Sciences is intended or should be inferred The authors gratefully acknowledge the assistance of Nadia Gunraj in data collection L Lipscombe was supported by the Canadian Diabetes Association’s Marsha HowarthSchwarz Postgraduate Fellowship J McLaughlin was 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
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