Metformin is associated with reduced risk of pancreatic cancer in patients with type 2 diabetes mellitus: a systematic review and meta-analysis.
OBJECTIVE
Recent epidemiological studies indicated that use of metformin might decrease the risk of various cancers among patients with type 2 diabetes mellitus (T2DM). However, its influence on pancreatic cancer was controversial. Therefore, we did a meta-analysis of currently available observational studies on the issue.


METHODS
We did a PubMed and ISI Web of Science search for observational articles. The pooled relative risk (RR) was estimated using a random-effect model. Heterogeneity was evaluated using I(2) statistic. Subgroup analysis was performed to explore the source of heterogeneity and confirm the overall estimates. Publication bias was also examined.


RESULTS
The analysis included 11 articles (13 studies) comprising 10 cohort studies and 3 case-control studies. Use of metformin was associated with a significant lower risk of pancreatic cancer [RR 0.63, 95% confidence internal (CI) 0.46-0.86, p=0.003]. In a total 11 subgroup analyses, 5 provided the consistent result with pooled effect estimates of overall analysis. No publication bias was detected by Begg's (Z=-0.79, p=0.428) and Egger's test (t=-0.92, p=0.378).


CONCLUSIONS
From present observational studies, use of metformin appears to be associated with a reduced risk of pancreatic cancer in patients with T2DM. Further investigation is needed.
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Zheng
Z
Wang
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Song-Tao
ST
Lai
Department of Statistics, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Li
L
Xie
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Jian-Dong
JD
Zhao
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Ning-Yi
NY
Ma
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Statistics, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Ji
J
Zhu
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China. Electronic address: zhigang-ren@163.com.
Zhi-Gang
ZG
Ren
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Guo-Liang
GL
Jiang
D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008687:Metformin / Q000627:therapeutic use*; D010190:Pancreatic Neoplasms / Q000517:prevention & control*; D011379:Prognosis; D018570:Risk Assessment
D007004:Hypoglycemic Agents; D008687:Metformin
Diabetes mellitus; Meta-analysis; Metformin; Pancreatic cancer