title: Effects of metformin on survival outcomes of lung cancer patients with type 2 diabetes mellitus: a meta-analysis.
abstract: BACKGROUND
  Anti-cancer effect of metformin on different kinds of lung cancer has been studied frequently. However, the association between metformin and the prognosis of lung cancer in type 2 diabetes patients is still controversial.
  
  
  METHODS
  An electronic search was conducted using PubMed/Medicine, EMBASE and Cochrane library databases. Statistical analyses were carried out using either random-effects or fixed-effects models according to the heterogeneity examined by I (2) statistics.
  
  
  RESULTS
  Six studies involving 2350 patients were included in the current meta-analysis. In all, the pooled HR of overall survival (OS) was 0.90 (95 % CI 0.84-0.96; P = 0.003). Sub-group analysis showed that when stratified by region the HR of OS was 0.52 (95 % CI 0.31-0.87; P = 0.012) and 0.86 (95 % CI 0.67-1.11, P = 0.361) for Asian and Western countries. When stratified by study design, the HR of OS was 0.78 (95 % CI 0.52-1.15, P = 0.206) and 0.82 (95 % CI 0.59-1.16, P = 0.264) for cohort and medical data-based studies. When stratified by lung cancer subtype, HR of OS was 0.52 (95 % CI 0.31-0.87; P = 0.012), 1.06 (95 % CI 0.51-2.19; P = 0.878) and 0.82 (95 % CI 0.59-1.16; P = 0.264) for SCLS, NSCLC and non-divided subtypes, respectively.
  
  
  CONCLUSIONS
  Metformin use may associate with a good prognosis in lung cancer patients with type 2 diabetes but the effect was modest. However, it could achieve benefits in a selective sub-group of lung cancer patients especially in SCLC patients from Asian. Further studies are warranted to confirm this efficacy.
authors.affiliation: Department of Respiratory, Affiliated Haian People's Hospital of Nantong University, 17 Cheng Zhong Ba Middle Road, Haian, 226600, Jiangsu, People's Republic of China.
authors.forename: R-H
authors.initials: RH
authors.lastname: Tian
authors.affiliation: Department of Respiratory, Shouguang People's Hospital, Shouguang, 262700, Shandong, People's Republic of China.
authors.forename: Y-G
authors.initials: YG
authors.lastname: Zhang
authors.affiliation: Department of Respiratory, Affiliated Haian People's Hospital of Nantong University, 17 Cheng Zhong Ba Middle Road, Haian, 226600, Jiangsu, People's Republic of China. zhenwu2210@126.com.
authors.forename: Z
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Respiratory, Affiliated Haian People's Hospital of Nantong University, 17 Cheng Zhong Ba Middle Road, Haian, 226600, Jiangsu, People's Republic of China. xialiu79@126.com.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Respiratory, Affiliated Haian People's Hospital of Nantong University, 17 Cheng Zhong Ba Middle Road, Haian, 226600, Jiangsu, People's Republic of China.
authors.forename: J-W
authors.initials: JW
authors.lastname: Yang
authors.affiliation: Department of Medical Affairs, Affiliated Haian People's Hospital of Nantong University, Haian, 226600, Jiangsu, People's Republic of China.
authors.forename: H-L
authors.initials: HL
authors.lastname: Ji
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008175:Lung Neoplasms / Q000150:complications* / Q000401:mortality*; D008687:Metformin / Q000627:therapeutic use*; D011379:Prognosis
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin
keywords: Diabetes; Lung cancer; Meta-analysis; Metformin; Prognosis