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Metformin may reduce oral cancer risk in patients with type 2 diabetes.

ABSTRACT: Whether metformin use may affect the risk of oral cancer required further investigation.The reimbursement database of the National Health Insurance in Taiwan was used. Patients with type 2 diabetes mellitus at an onset age of 25-74 years during 1999-2005 and newly treated with either metformin (n = 288198, "ever users of metformin") or other antidiabetic drugs (n = 16263, "never users of metformin") were followed for at least 6 months for oral cancer until December 31, 2011. The treatment effect of metformin (for ever versus never users, and for tertiles of cumulative duration of therapy) was estimated by Cox regression adjusted for propensity score (PS) or incorporated with the inverse probability of treatment weighting (IPTW) using PS.The respective numbers of incident oral cancer in ever users and never users were 1273 (0.44%) and 119 (0.73%), with respective incidences of 92.7 and 163.6 per 100,000 person-years. The overall hazard ratios (95% confidence intervals) suggested a significantly lower risk [0.584 (0.483-0.707) for PS-adjusted model, and 0.562 (0.465-0.678) for IPTW model]. In tertile analyses, the PS-adjusted hazard ratios (95% confidence intervals) for the first (<21.5 months), second (21.5-45.9 months) and third (>45.9 months) tertile of cumulative duration were 1.403 (1.152-1.708), 0.557 (0.453-0.684) and 0.152 (0.119-0.194), respectively; and were 1.244 (1.024-1.511), 0.526 (0.429-0.645) and 0.138 (0.108-0.176), respectively, for IPTW.Metformin may significantly reduce the risk of oral cancer, especially when the cumulative duration is more than 21.5 months.

SUBMITTER: Tseng CH

PROVIDER: S-EPMC4811512 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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Metformin may reduce oral cancer risk in patients with type 2 diabetes.

Tseng Chin-Hsiao CH

Oncotarget 20160101 2

<h4>Background</h4>Whether metformin use may affect the risk of oral cancer required further investigation.<h4>Methods</h4>The reimbursement database of the National Health Insurance in Taiwan was used. Patients with type 2 diabetes mellitus at an onset age of 25-74 years during 1999-2005 and newly treated with either metformin (n = 288198, "ever users of metformin") or other antidiabetic drugs (n = 16263, "never users of metformin") were followed for at least 6 months for oral cancer until Dece ...[more]

PMID: 26683519

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Project description:The epidemiological literature suggests that insulin resistance, hyperinsulinemia, and increased levels of insulin-like growth factors place patients with type 2 diabetes mellitus (T2DM) at greater risk of cancer. The association between cancer incidence and the use of antidiabetic medications in patients with T2DM has been recently examined. There have been conflicting reports regarding an association between metformin and cancer risk. The aim of this study was to investigate the relationship between metformin use and the incidence of cancer in Koreans with T2DM.Data from The Korean National Diabetes Program (KNDP, 2006-2014), a nationwide, large-scale, prospective, multicenter cohort study in Korea, were used to study patients with T2DM. Patients ≥30 years old whose complete medical records were available were included in this study. Patients with a history of any cancer on KNDP registration or those who had been diagnosed with any type of cancer within 1 year of metformin use were excluded. Survival curves with respect to the incidence of cancer were plotted using the Kaplan-Meier method. Hazard ratios and 95% confidence intervals for cancer were estimated in a Cox proportional hazards regression analysis.During a mean 5.8 years of follow-up, 164 of the 1918 study patients (335 metformin nonusers and 1583 metformin users) developed cancer. The incidence per 1000 person-years was 21.8 in metformin nonusers and 13.2 in metformin users. Metformin users had a reduced risk of cancer, even after adjustment for demographic characteristics, metabolic parameters, diabetic complications, and other antidiabetic medications (hazard ratio 0.513, 95% confidence interval 0.318-0.826, P = .0060). Subgroup analysis of metformin users showed a reduced risk of cancer in males, patients < 65 years of age, patients with a T2DM duration < 5 years, nonobese patients, nonsmokers, and good glycemic control group.This large-scale, prospective, multicenter cohort study demonstrated an association between metformin use and reduced cancer risk in patients with T2DM.

Project description:BackgroundType 2 diabetes (T2D) has been associated with increased breast cancer risk, but commonly prescribed antidiabetic medications such as metformin may reduce risk. Few studies have investigated T2D and medications together in relation to breast cancer.Patients and methodsData came from 44 541 Sister Study participants aged 35 to 74 years at enrollment (2003-2009) who satisfied eligibility criteria, followed through 15 September 2017. Information on time-varying, self-reported, physician-diagnosed, prevalent and incident T2D, use of antidiabetic medications, and covariates was obtained from baseline and follow-up questionnaires. Incident breast cancers were confirmed with medical records. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated.ResultsDuring follow-up (median, 8.6 years), 2678 breast cancers were diagnosed at least 1 year after enrollment. There were 3227 women (7.2%) with prevalent and 2389 (5.3%) with incident T2D, among whom 61% (n = 3386) were ever treated with metformin. There was no overall association between T2D and breast cancer risk (HR 0.99; 95% CI, 0.87-1.13). However, T2D was associated with increased risk of triple-negative breast cancer (HR 1.40; 95% CI, 0.90-2.16). Compared with not having T2D, T2D with metformin use was not associated with overall breast cancer risk (HR 0.98; 95% CI, 0.83-1.15), but it was associated with decreased risk of estrogen receptor (ER)-positive breast cancer (HR 0.86; 95% CI 0.70-1.05) and increased risk of ER-negative (HR 1.25; 95% CI, 0.84-1.88) and triple-negative breast cancer (HR 1.74; 95% CI, 1.06-2.83). The inverse association with ER-positive cancer was stronger for longer duration (≥10 year) metformin use (HR 0.62; 95% CI, 0.38-1.01; P for trend = 0.09). Results were supported by sensitivity analyses.ConclusionOur findings suggest that associations between T2D and breast cancer may differ by hormone receptor status and that associations between T2D and ER-positive breast cancer may be reduced by long-term metformin use.

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Metformin may reduce oral cancer risk in patients with type 2 diabetes.

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Metformin may reduce oral cancer risk in patients with type 2 diabetes.

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