Association of antidiabetic medication and statins with breast cancer incidence in women with type 2 diabetes

Mayu Hosio,Arja Jukkola,Martti Arffman,Peeter Karihtala,Ulla Puistola,Esa Läärä,Elina Urpilainen,Mikko Marttila,Reijo Sund,Ari Hautakoski

doi:10.1007/s10549-019-05185-0

Abstract

PurposeTo 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).MethodsData 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.Results2300 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.ConclusionsNo 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.

Highlights

Breast cancer is globally the most common cancer among females in both developed and developing countries [1]
Increasing cumulative use of insulin was observed to be positively associated with the risk of breast cancer in a monotonic manner
Metformin use seems to be related to a lowered breast cancer incidence [23,24,25,26], at least in connection with long-term metformin use [27, 28]

Summary

Introduction

Breast cancer is globally the most common cancer among females in both developed and developing countries [1]. People with type 2 diabetes (T2D) have a higher risk of developing breast cancer [3, 4]. It has been suggested that metformin may decrease breast cancer risk [5], but on the basis of a meta-analysis, there is insufficient evidence to support this hypothesis [6]. Many preclinical studies have shown anticancer effects of metformin in breast cancer and in other types of cancer [7,8,9]. It has been suggested that the use of glargine (a long-acting insulin analogue that is used in patients with diabetes) is associated with an increased incidence of breast cancer [11]

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Results

Conclusion