Certain indications suggest that EGFR and its ligands (epidermal growth factor (EGF), amphiregulin, HB-EGF, TGF-alpha) can be applied as serological biomarkers in relation to the prognosis and prediction of response to EGFR-targeted treatments in lung [36], ovarian [37], and colorectal cancer [38]. Here, EGFR is linked to colorectal cancer.