Fig. 2

EGFR-ligands-based molecular staging outperforms the TNM system in predicting patient prognosis. a The TNM staging was unable to predict patients five-year survival (Kaplan-Meier curve, Log rank test, p = 0.08). b Expressing more than median mRNA levels of either none, one, two, three or four of the EGFR ligands (i.e. AREG, EGF, HBEGF and BCT) was significantly linked to reduced five-year survival (Kaplan-Meier curve, Log rank test, p < 0.001). Whereas only 14 % of the patients (4/29) with tumors that expressed less than median mRNA levels of the four EGFR ligands died within five years, the number of death increased as the number of higher-than-median expressing ligands increased to one (25 %, 25/100), two (31 %, 44/142), three (35 %, 34/97) or four (45 %, 14/31). c EGFR-ligand mRNA expression predicted patient survival with TNM stage IV disease (Kaplan-Meier curve, Log rank test, p = 0.004). Whereas only 26 % (14/54) of patients died within five years if the OSCCs expressed increased mRNA for none or one of the EGFR-ligands, it increased to 32 % (23/71) and 45 % (30/67) if the tumors expressed increased mRNA for two, or three to four EGFR-ligands, respectively. d Patients with over-median-AREG-expressing tumors had worse prognosis than patients expressing any of the other three ligands in the single-ligand-expressing group (Kaplan-Meier curve, Log rank test, p = 0.04)