Nickan Research Institute Immunopathologia Persa 2423-8015 5 1 2019 01 01 Administration of metformin to increase the efficacy of chemotherapy regimen in cancers; a new look to an old drug e11 e11 10.15171/ipp.2019.11 EN Niloufar Hooshyar https://orcid.org/0000-0002-6167-6747 Ramin Tolouian https://orcid.org/0000-0003-2242-9310 Behzad Ghasemi https://orcid.org/0000-0001-9600-9728 Nafiseh Nowrouzi https://orcid.org/0000-0002-3734-8583 Banafsheh Yalameha https://orcid.org/0000-0002-3386-0264 Mohammadreza Khosravifarsani https://orcid.org/0000-0003-4271-7846 Parto Nasri https://orcid.org/0000-0002-9596-8860 Journal Article 10.15171/ipp.2019.11 2019 01 14 2019 04 08 Chemotherapeutic agents are still the major and most common therapy to prevent tumor growth. These drugs have various adverse effects in different organs in addition to systemic effects. Finding more specific and effective drugs or new adjuvant therapeutic substance is needed to improve the success rate. Several studies have proposed the possible mechanisms of anti-neoplastic of metformin, however, its exact mechanism is still obscure. The suggested mechanisms are; alteration in the host metabolic environment after administration of metformin, such as decreases in insulin-dependent stimulation of tumor growth or direct effect on cancer cells, such as the impact on adenosine monophosphate (AMP)-activated protein kinase signaling pathway. Metformin, as an adjuvant therapy, synergistically exerts growth inhibitory effects against cell growth and can induce cell apoptosis in an animal model. Adding metformin to the chemotherapy regimen may reduce resistance and enhance therapeutic efficacy.