Research progress on the therapeutic effect and mechanism of metformin for lung cancer (Review).

Lung cancer is the most common type of cancer and the leading cause of cancer‑associated death worldwide. Despite the availability of various treatments such as surgery, chemoradiotherapy, targeted drugs and immunotherapy, treatment is expensive and the prognosis remains poor. At present, lung cancer drugs and treatment programs remain in a state of continuous exploration and research to improve the prognosis, and to reduce the pain and economic burden for the patients. Type 2 diabetes is a common chronic disease in middle‑aged and elderly patients, leading to significantly increased complications of cardiovascular and cerebrovascular diseases. Epidemiology shows that type 2 diabetes also increases the incidence of malignant tumors, including lung, liver, colorectal and pancreatic cancer. Metformin is a biguanide, widely used as a first‑line oral drug in treating type 2 diabetes. Metformin has a hypoglycemic effect and a biological antitumor impact, reducing the incidence of various tumors, including lung cancer, and improving the prognosis of patients with tumors. The anti‑lung cancer effect of metformin involves a variety of mechanisms that can improve the therapeutic effect and prognosis of lung cancer, as a single drug or in combination with other therapies. The present study aims to review the associated literature and the therapeutic effects of metformin on lung cancer.