Cancer antigen (CA)

Cancer antigen is a broad, collective term for substances produced by tumor cells that can elicit an immune response or be exploited as therapeutic targets (NCI Dictionary, 2024). These molecules are typically classified into tumor-specific antigens (TSAs), which are unique to malignant cells, and tumor-associated antigens (TAAs), which are present on both normal and cancerous cells but often overexpressed in the latter (Abbas et al., Cellular and Molecular Immunology). Because the term encompasses a vast range of proteins, carbohydrates, and lipids—including well-known targets like HER2, CD20, and MUC1—it does not refer to a single molecular entity but rather a functional class of biomarkers and therapeutic handles (Vigneron, 2015). In clinical oncology, cancer antigens are utilized for diagnostic screening, monitoring treatment efficacy, and developing precision medicines such as monoclonal antibodies and CAR-T cell therapies (Parmiani et al., 2002). The effectiveness of targeting these antigens is often limited by the heterogeneity of tumor expression and the potential for "on-target, off-tumor" toxicity in healthy tissues. Consequently, the identification of highly specific neoantigens remains a primary focus of modern personalized cancer immunotherapy to improve safety and efficacy.

Other names

Tumor antigenTumor-associated antigen (TAA)Tumor-specific antigen (TSA)Neoantigen

Cancer antigens serve as targets for monoclonal antibodies, CAR-T cells, and vaccines to induce immune-mediated tumor destruction via mechanisms such as antibody-dependent cellular cytotoxicity (ADCC) or direct T-cell recognition.