Metformin may reduce breast cancer risk in Taiwanese women with type 2 diabetes
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Whether metformin therapy affects breast cancer risk in Asian patients with type 2 diabetes mellitus (T2DM) has not been investigated. The reimbursement databases of Taiwanese female patients with a new diagnosis of T2DM between 1998 and 2002 (n = 476,282) were retrieved from the National Health Insurance for follow-up of breast cancer until the end of 2009. Metformin was treated as a time-dependent variable; and of these patients, 285,087 were never-users and 191,195 were ever-users. A time-dependent approach was used to calculate breast cancer incidence and estimate hazard ratios by Cox regression for ever-users, never-users, and subgroups of metformin exposure (tertiles of cumulative duration and cumulative dose). During follow-up, 2,412 (1.26 %) metformin ever-users and 9,322 (2.10 %) never-users developed breast cancer, representing an incidence of 201.08 and 535.88 per 100,000 person-years, respectively. The overall multivariable-adjusted hazard ratio (95 % confidence intervals) for ever- versus never-users was 0.630 (0.597–0.665). The multivariable-adjusted hazard ratios for the first, second, and third tertiles of cumulative duration of metformin therapy were 1.122 (1.043–1.207), 0.754 (0.692–0.820), and 0.280 (0.253–0.310), respectively, (P-trend <0.0001); and 1.099 (1.021–1.182), 0.664 (0.611–0.723), and 0.311 (0.281–0.344), respectively, (P-trend <0.0001), for cumulative dose of metformin. Metformin use is associated with a decreased risk of breast cancer.
KeywordsBreast cancer Diabetes Epidemiology Metformin Taiwan
The study was supported by the National Science Council (NSC102-2314-B-002-067) of Taiwan.
Conflict of interest
- 4.Bureau of Health Promotion (2010) Cancer Registry Annual Report 2008. Department of Health, Executive Yuan, Taiwan. http://www.bhp.doh.gov.tw/Download%5C97Statistics%5C1.%E7%99%8C%E7%97%87%E7%99%BB%E8%A8%98%E5%B9%B4%E5%BA%A6%E5%A0%B1%E5%91%8A%EF%BC%88%E5%85%A8%EF%BC%89/Y97-%E7%99%8C%E7%97%87%E7%99%BB%E8%A8%98%E5%B9%B4%E5%BA%A6%E5%A0%B1%E5%91%8A%EF%BC%88%E5%85%A8).pdf. Accessed 27 June 2012
- 9.Gerhard T (2008) Bias: considerations for research practice. Am J Health Syst Pharm. 65:2159–68. Erratum in: Am J Health Syst Pharm. 2008;65:2192Google Scholar
- 17.Kato K, Gong J, Iwama H, Kitanaka A, Tani J, Miyoshi H, Nomura K, Mimura S, Kobayashi M, Aritomo Y, Kobara H, Mori H, Himoto T, Okano K, Suzuki Y, Murao K, Masaki T (2012) The antidiabetic drug metformin inhibits gastric cancer cell proliferation in vitro and in vivo. Mol Cancer Ther 11:549–560PubMedCrossRefGoogle Scholar
- 18.Anisimov VN, Berstein LM, Egormin PA, Piskunova TS, Popovich IG, Zabezhinski MA, Kovalenko IG, Poroshina TE, Semenchenko AV, Provinciali M, Re F, Franceschi C (2005) Effect of metformin on life span and on the development of spontaneous mammary tumors in HER-2/neu transgenic mice. Exp Gerontol 40:685–693PubMedCrossRefGoogle Scholar
- 22.Thompson AM (2014) Molecular pathways: preclinical models and clinical trials with metformin in breast cancer. Clin Cancer ResGoogle Scholar