BackgroundOvarian cancer is one of the most lethal cancers and women with type 2 diabetes (T2D) have even poorer survival from it. We assessed the prognosis of ovarian cancer in women with type 2 diabetes treated with metformin, other forms of antidiabetic medication, or statins.MethodsStudy cohort consisted of women with T2D diagnosed with ovarian cancer in Finland 1998–2011. They were identified from a nationwide diabetes database (FinDM), being linked to several national registers. Patients were grouped according to their medication in the three years preceding ovarian cancer diagnosis. The Aalen–Johansen estimator was used to describe cumulative mortality from ovarian cancer and from other causes in different medication groups. Mortality rates were analysed by Cox models, and adjusted hazard ratios (HR) with 95% confidence intervals (95% CIs) were estimated in relation to the use of different forms of medication. Main outcome measures were death from ovarian cancer and death from other causes.ResultsDuring the accrual period 421 newly diagnosed ovarian cancers were identified in the FinDM database. No evidence was found for any differences in mortality from ovarian cancer or other causes between different antidiabetic medication groups. Pre-diagnostic use of statins was observed to be associated with decreased mortality from ovarian cancer compared with no such use (HR 0.72, 95% CI 0.56–0.93).ConclusionsOur findings are inconclusive as regards the association between metformin and ovarian cancer survival. However, some evidence was found for improved prognosis of ovarian cancer with pre-diagnostic statin use, requiring cautious interpretation, though.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4676-z) contains supplementary material, which is available to authorized users.

In our study the use of metformin or other oral forms of ADM was not associated with a lowered risk of endometrioid EC in women with T2D. Instead statins were observed to be inversely associated with endometrioid EC in this population.

No evidence found for metformin or statins reducing the incidence of ovarian cancer.

Purpose To address the possible association between the use of metformin, other forms of antidiabetic medication (ADM) and statins with the incidence of breast cancer in women with type 2 diabetes (T2D). Methods Data were collected from a Finnish nationwide diabetes database (FinDM). The study cohort consisted of women diagnosed with T2D in 1996–2011 in Finland. In full-cohort analysis, Poisson regression was used to estimate hazard ratios (HRs) in relation to use of metformin, insulin, other forms of oral ADM and statins. In nested case–control analysis, up to 20 controls were matched for age and duration of diabetes to each case of breast cancer. Conditional logistic regression was used to estimate HRs in relation to medication use and cumulative use of different forms of ADM, and statins. Results 2300 women were diagnosed with breast cancer during follow-up. No difference in breast cancer incidence was observed between metformin users [HR 1.02, 95% confidence interval (CI) 0.93–1.11] or statin users (HR 0.97, 95% CI 0.89–1.05) compared with non-users. In nested case–control analysis the results were similar. Use of insulin (HR 1.18, 95% CI 1.03–1.36) was associated with a slightly increased incidence of breast cancer. Conclusions No evidence of an association between the use of metformin or statins and the incidence of breast cancer in women with T2D was found. Among insulin users, a slightly higher incidence of breast cancer was observed. Electronic supplementary material The online version of this article (10.1007/s10549-019-05185-0) contains supplementary material, which is available to authorized users.

Background: We assessed survival of breast cancer in women with type 2 diabetes (T2D) treated with metformin, other types of antidiabetic medication (ADM) and statins. Materials and Methods: The study cohort consisted of women with T2D and diagnosed with breast cancer in Finland in 1998─2011. Mortality rates from breast cancer and other causes were analysed by Cox models, and adjusted hazard ratios (HRs) with 95% confidence intervals (Cls) were estimated in relation to the use of different types of medication. Results: The final cohort consisted of 3,533 women. No clear evidence was found for breast cancer mortality being different in metformin users (HR 0.86, 95% Cl 0.63-1.17), but their other-cause mortality appeared to be lower (HR 0.73, 95% Cl 0.55-0.97) in comparison with women using other types of oral ADM. Other-cause mortality was higher among insulin users (HR 1.45, 95% Cl 1.16-1.80) compared with users of other oral ADMs, other than metformin. Prediagnostic statin use was observed to be associated with decreased mortality from both breast cancer (HR 0.76, 95% Cl 0.63-0.92) and other causes (HR 0.75, 95% Cl 0.64-0.87). Conclusions: We did not find any association between ADM use and disease-specific mortality among women with T2D diagnosed with breast cancer. However, interestingly, prediagnostic statin use was observed to predict reduced mortality from breast cancer and other causes. We hypothesise that treating treatment practices of T2D or hypercholesterolaemia of breast cancer patients might affect overall prognosis of women diagnosed with breast cancer and T2D.