STAT3 and cancer: miRNAs as suppressors or oncogenes influence inflammatory molecules and regulate the secretion of cytokines (interleukins, TNF-α, transforming growth factor-β (TGFβ), granulocyte-macrophage colony-stimulating factor (GM-CSF), chemokines transcription factors (nuclear factor kB (NF-kB), and signal transducer and activator of transcription 3 (STAT3)), and play a crucial role in the development of cancer-related inflammation and functioning of immune cells and immunity system.