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.

This meta-analysis suggested that the I/D polymorphism of ACE gene would be a risk factor of asthma. To further evaluate gene-to-gene and gene-to-environment interactions between polymorphisms of ACE gene and asthma risk, more studies with large groups of patients are required.