AFP and cancer: Many biomarkers associated with cancer have been found and can be used for cancer diagnosis, such as carcinoembryonic antigen (CEA) [3,4,5,6,7], alpha-fetoprotein (AFP) [8,9], prostate-specific antigen (PSA) [10], carbohydrate antigen (CA) [11,12], neuron-specific enolase (NSE) [13], etc.