PMC4433365_01
The study design and data extraction workflow for patients in the Vanderbilt electronic health record (EHR) system from January 1995 to December 2010.
ocu907f1p.jpg
PMC4433365_01_ocu907f1p.jpg
AMIAJNL2014002649F1
We identified 42 165 individuals with an incident cancer diagnosis (excluding skin cancer and CHF/CKD, and age >=18 years old) between January 1, 1995 and December 31, 2010 (figure 1) at Vanderbilt. Mayo cancer population and most associations by cancer type (breast, colorectal, lung, and prostate) were statistically significant, likely due to larger sample sizes in the Mayo cohort. Metformin was also associated with improved survival in other cancers types in at least one EHR, including bone marrow, gynecologic, genitourinary, and gastrointestinal (see online supplementary appendix figure 1).
The study design and data extraction workflow for patients in the Mayo Clinic electronic health record (EHR) system from January 1995 to December 2010.
ocu907f2p.jpg
PMC4433365_01_ocu907f2p.jpg
AMIAJNL2014002649F2
A1c of 7.6%. At Mayo Clinic, we identified 79 258 patients in four exposure groups (figure 2 and table 2).
Kaplan-Meier (K-M) plot of overall cancer survival for the Vanderbilt and Mayo Clinic cohorts. DM2, type 2 diabetes mellitus.
ocu907f3p.jpg
PMC4433365_01_ocu907f3p.jpg
AMIAJNL2014002649F3
Adjusted HRs by cancer type for the Vanderbilt and Mayo cohorts. Other, DM2 cancer patients on other drugs; Insulin, DM2 cancer patients on insulin only; Metf, DM2 cancer patients on metformin; None, cancer patients without DM2.
ocu907f4p.jpg
PMC4433365_01_ocu907f4p.jpg
AMIAJNL2014002649F4
Reduced mortality was also observed for metformin compared to cancer patients without diabetes (HR 0.77; 95% CI 0.71 to 0.85) (figure 4). We replicated our findings for overall mortality after a cancer diagnosis in the Mayo Clinic cohort with HRs and 95% CIs as follows: HR 0.70 (95% CI 0.63 to 0.77), HR 0.65 (95% CI 0.58 to 0.73), and HR 0.59 (95% CI 0.54 to 0.65) (figure 4), comparing the metformin group versus other drugs, insulin only, and non-diabetic groups, respectively.       The impact of metformin on mortality varied by cancer type and also by exposure group (figure 4).
Adjusted Cox proportional hazards model stratified by tumor stage for the Vanderbilt cohort. All models are based on cancer survival in a smoking white male, age 58 years, body mass index 27 kg/m2, with a cancer other than the four most common tumor types, and not using insulin. DM2, type 2 diabetes mellitus.
ocu907f5p.jpg
PMC4433365_01_ocu907f5p.jpg
AMIAJNL2014002649F5
We present the adjusted overall cancer survival curves for each tumor stage in figure 5.
Adjusted Cox proportional hazards model stratified by tumor type for the Vanderbilt cohort. All models are based on cancer survival in a white smoker, age 58 years, body mass index 27 kg/m2, and not using insulin. DM2, type 2 diabetes mellitus.
ocu907f6p.jpg
PMC4433365_01_ocu907f6p.jpg
AMIAJNL2014002649F6
Predicted survival curves for colorectal, lung, breast, and prostate cancer show patients on metformin had improved survival for each specific cancer (figure 6).