Table 1.

Previous studies which evaluated the predictive biomarker of severity of skin toxicity induced by anti- epidermal growth factor receptor antibody treatment in colorectal cancer

Ref.	Methods	Predictive markers	Risk factors of severe skin toxicity
Jatoi et al[39] (2009)	Patient's backgrounds	Age	Younger
		Gender	Men
Graziano et al[40] (2008)	EGFR polymorphism	CA repeat in EGFR intron-1	EGFR intron-1 S/S variant
Vallböhmer et al[42] (2005)	mRNA expression	Cox-2	Low expression
Takahashi et al[43,44] (2014, 2015)	Serum levels of ligands	AREG, EREG, HGF	Low levels of ligands at pre-treatment

EGFR: Epidermal growth factor receptor; Cox-2: Cyclo-oxygenase 2; AREG: Amphilegulin; EREG: Epiregulin; HGF: Hepatocyte growth factor.