Abstract 259P
Background
Several studies suggest improved breast cancer (BrCa) outcomes for women taking metformin and other oral hypoglycaemic agents (OHAs), raising the possibility as preventative or therapeutic agents. No such evidence exists for Indigenous women with breast cancer. Here, we examine the impact of metformin and other OHAs on BrCa specific and all-cause mortality.
Methods
We reviewed 208 Indigenous BrCa patients identified within the WA cancer registry. Patients were sub-categorized by diabetic status, use of OHAs, BrCa sub-type and stage. Kaplan Meier analyses evaluated BrCa and all-cause mortality. Regression analysis and correlation models determined associations between OHAs and survivals.
Results
108 patients (52%) were diabetic. Of these, 69 received metformin, 43 sulfonylureas, 7 thiazolideniodiones, 21 DPP inhibitors, and 32 insulin. Age of diabetics were 58.6 yr v 53.2 yr,p=0.0018. Metformin prescribed more to luminal patients v non-luminal (57 v 26%, p=0.002); luminal diabetics on metformin were 71% v 55 % non-luminal,p= 0.18 After a median follow-up of 10 years, the full diabetic cohort had a non-significant trend to shorter median overall survival (OS) relative to non-diabetics (91.5 v 99.8 months, p=0.13). The median OS of all patients taking OHAs was similar to those not (95 v 96 months, p=0.7). Those on metformin had a numerically longer median OS (95 v 88 months, p=0.20) whereas those on sulfonylureas and those on insulin had numerically shorter median OS (92 v 97 months, p=0.2 and 92 v 97 months, p=0.3 respectively). BrCa specific median survival was 36 v 47 months for non-cancer related deaths, p =0.3. No impact of OHAs was noted when examining different sub-types. Regression analysis revealed no significant association of metformin (p=0.50), T2DM with metformin (p=0.14), cause of mortality (0.22) with survival time and mortality. Further, correlation analysis suggest strong negative correlation was observed among them (r = -0.84, p<0.0001).
Conclusions
Metformin had no significant impact on survival outcomes in diabetic Indigenous patients with BrCa. Analysis of metabolic syndrome and diabetes in the context of a larger cohort is needed to exclude impact of anti-diabetic pharmacotherapy on prognosis.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
A. Khan and A. Redfern.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.