The Association of Metformin, Other Antidiabetic Medications, and Statins With the Prognosis of Colon Cancer in Patients With Type 2 Diabetes: A Retrospective Cohort Study.

BACKGROUND: Use of metformin and statins have been associated with improved prognosis of colon cancer (CC) in patients with type 2 diabetes (T2D). We examined the survival from CC in relation to the use of metformin, other oral antidiabetic medications (ADM), insulin, and statins in T2D patients. MATERIALS AND METHODS: A cohort (n = 2252) of persons with pre-existing T2D diagnosed with incident CC between 1998 and 2011 was identified from several Finnish registers. Cox models were fitted for cause-specific mortality rates to obtain adjusted estimates of the hazard ratios (HR) with 95% confidence intervals (CI) in relation to use of ADM and statins before the CC diagnosis. Cox models were also fitted for mortality in relation to post-diagnostic use of the medications treating these as time-dependent exposures, and starting follow-up 1 year after the CC diagnosis. RESULTS: Pre- and post-diagnostic metformin use was weakly associated with the risk of CC-related death (HR .75; 95% CI .58-.99, and HR .78; 95% CI .54-1.14, respectively) compared to the use of other oral ADMs. Pre- and post-diagnostic statin use predicted a reduced risk of CC-related death (HR .83; 95% CI .71- .98, and HR .69; 95% CI .54-.89, respectively). CONCLUSION: Additional evidence was found for use of statins being associated with an improved survival from CC in patients with pre-existing T2D, but for metformin use the evidence was weaker.

The Association of Metformin, Other Antidiabetic Medications and Statins on the Prognosis of Rectal Cancer in Patients with Type 2 Diabetes: A Retrospective Cohort Study.

Metformin and statin use have been associated with an improved prognosis for colorectal cancer in persons with type 2 diabetes (T2D). Data regarding rectal cancer (RC) have been inconclusive; therefore, we investigated the issue with high-quality data and a robust study design. We identified 1271 eligible patients with T2D and incident RC between 1998 and 2011 from the Diabetes in Finland (FinDM) database. Cox models were fitted for cause-specific mortality rates to obtain adjusted estimates of the hazard ratios (HR) with 95% confidence intervals (CI) in relation to use of antidiabetic medication (ADM) and statins before the RC diagnosis and for post-diagnostic use in a time-dependent exposure manner. No sufficient evidence was found for either pre- or post-diagnostic metformin use and RC mortality (HR 0.96, 95% CI 0.67-1.38, and 0.70, 95% CI 0.45-1.10, respectively) when compared to other oral ADMs. Both pre- and post-diagnostic statin use appeared to be inversely associated with mortality from RC (HR 0.77 95% CI 0.63-0.94, and 0.57, 95% CI 0.42-0.78, respectively). Our study was inconclusive as to the association of metformin use with the prognosis of RC, but statin use was found to predict reduced mortality, both from RC and from other causes of death in persons with T2D.

Association of Metformin, Other Antidiabetic Medications, and Statins With Incidence of Colon Cancer in Patients With Type 2 Diabetes.

BACKGROUND: Metformin and statins may have anticancer effects, with plausible cellular mechanisms. However, the association of these agents with the risk of colorectal cancer is unclear. PATIENTS AND METHODS: This was a retrospective cohort study on a large population (N = 316,317) of patients with type 2 diabetes. Data were obtained from the Diabetes in Finland database (FinDM). In a full cohort analysis, hazard ratios (HRs) with their 95% confidence intervals (CIs) for ever use versus never use were estimated using a multiple Poisson regression model. A nested case-control design within the cohort was used to examine the association of colon cancer (CC) with the defined daily dose of medication. The data were analyzed by conditional logistic regression. The analyses were adjusted for the patient's age, sex, and duration of diabetes. RESULTS: In total, 1351 CC cases were diagnosed during 1996-2011. The results revealed insufficient evidence for an association between metformin (HR, 1.01; 95% CI, 0.90-1.14), other oral antidiabetic medications (HR, 1.05; 95% CI, 0.93-1.19), insulin (HR, 1.02; 95% CI, 0.86-1.22), or statins (HR, 0.94; 95% CI, 0.84-1.05) and the incidence of CC in the full cohort analysis. The results from the case-control study were similar, with no consistent trend in the incidence of CC according to the cumulative dose of metformin or the other studied medications. CONCLUSION: This study found insufficient evidence for an association between metformin, insulin, other oral type 2 diabetes medications, or statins and the incidence of CC.