Lung tumor markers of cytokeratin origin: an overview

Lung tumor markers fall into several categories including oncofetal proteins, structural proteins and their fragments, enzymes, membrane antigens, peptide and non-peptide hormones. Cytokeratins (CK) are well known structural proteins whose degradation gives rise to soluble fragments, measurable in the blood of patients and capable of cancer marking. Among them, Tissue Polypeptide Antigen (TPA), Tissue Polypeptide-Specific Antigen (TPS) and Cytokeratin-19-Fragments (Cyfra 21-1) are the most studied CK fragments' complexes. This article will review biological characteristics and clinical properties of these substances, emphasizing as their concentration in the peripheral blood might reflect the mass of tumor, the rate of cancer cell lysis, and other potentially unfavorable tumor characteristics. Assaying the concentration of CK fragments in the blood is an easy and effective way to assess lung cancer and monitor its clinical evolution.