Fig. 1.

Tumor antigen classification and characteristics. Generally, tumor antigens are classified into tumor-associated and tumor-specific antigens. According to the expression levels and tissue expression characteristics, tumor-associated antigens can be further divided into overexpressed antigens, cancer testis antigens, differentiation antigens, oncoviral antigens and oncofoetal antigens. There are two ways to classify tumor-specific antigens, according to their origin, they can be classified as antigens derived from genetic mutations and antigens derived from abnormal expression regulation; according to clinical setting, they can be classified as guarding antigens, restrained antigens, and ignored antigens