Table of Contents
ISRN Endocrinology
Volume 2013, Article ID 636927, 9 pages
Review Article

Risk of Cancer in Diabetes: The Effect of Metformin

Endocrine Research Center (Firouzgar), Institute of Endocrinology and Metabolism, Tehran University of Medical Sciences, Tehran 15937-48711, Iran

Received 20 July 2013; Accepted 16 August 2013

Academic Editors: A. Kautzky-Willer and N. Tentolouris

Copyright © 2013 Mojtaba Malek et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Cancer is the second cause of death. Association of diabetes as a growing and costly disease with cancer is a major health concern. Meanwhile, preexisting diabetes is associated with an increased risk of all-cause and cancer-specific mortalities. Presence of diabetes related comorbidities, poorer response to cancer treatment, and excess mortality related to diabetes are among the most important explanations. Although diabetes appear to be a risk factor for cancer and is associated with the mortality risk in cancer patients, several factors such as diabetes duration, multiple drug therapy, and the presence of diabetes comorbidities make the assessment of the effect of diabetes treatment on cancer risk and mortality difficult. Metformin is the drug of choice for the treatment of type 2 diabetes. The available evidence from basic science, clinical, and population-based research supports the anticancer effect of metformin. However, randomized controlled clinical trials do not provide enough evidence for a strong protective effect of metformin on cancer incidence or mortality. One of the most important limitations of these trials is the short duration of the followup. Further long-term randomized controlled clinical trials specifically designed to determine metformin effect on cancer risk are needed to provide the best answer to this challenge.