Diabetes Mellitus and Breast Cancer Outcomes

Back ground and aim: Diabetes mellitus and cancer are major causes ofmorbidity and death worldwide. Recent research has focused attention on theeffect of comorbid conditions on all-cause mortality in women with breastcancer. Potential interactions between diabetes and breast cancer, in particular,are complex. The goal of this review is examining the effect of pre-existingdiabetes on breast cancer–related outcomes.Methods : This is a review article that searched EMBASE and MEDLINEdatabases from inception through July 1, 2009, using search terms related todiabetes mellitus, cancer, and prognostic outcome. Studies were included if theyreported a prognostic outcome by diabetes status, evaluated a cancer population,and contained original data published in the English language. A meta-analysisof pre-existing diabetes and its effect on all-cause mortality in patients withbreast cancer and qualitatively summarized other prognostic outcomes were bedone . Of 8,828 titles identified, eight articles met inclusion/exclusion criteriaand described outcomes in patients with breast cancer and diabetes.Results: Pre-existing diabetes was significantly associated with all-causemortality in six of seven studies. In a meta-analysis, patients with breast cancerand diabetes had a significantly higher all-cause mortality risk (pooled hazardratio [HR], 1.49; 95% CI, 1.35 to 1.65) compared with their non-diabeticcounterparts. Three of four studies found pre-existing diabetes to be associatedwith more advanced stage at presentation. Diabetes was also associated withaltered regimens for breast cancer treatment and increased toxicity fromchemotherapy.Conclusion Patients with breast cancer and pre-existing diabetes compared withtheir non-diabetic counterparts, have a greater risk of death and tend to presentat later stages and receive altered treatment regimens. Studies are needed toinvestigate pathophysiologic interactions between diabetes and breast cancerand determine whether improvements in diabetes care can reduce mortality inpatients with breast cancer