STAT3 activation was recently suggested as a potential predictive marker for resistance to EGFR TKI therapies in patients with metastatic colorectal cancer (mCRC) and non-small cell lung cancer (NSCLC), given the correlation between the activation of STAT3 and resistance of cells to EGFR TKI therapy [30, 31]. This evidence concerns the gene STAT3 and metastatic colorectal cancer.