Usefulness of serum carboxy-terminal telopeptide of type I collagen (ICTP)as a marker of bone metastasis from lung cancer

Background: Serum pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP) is a metabolite of type I collagen comprising 90% o r more of organic substances in bone. Its usefulness as a marker of bone me tastasis from malignant tumors is expected. Method: We measured ICTP to evaluate its clinical usefulness for diagnosis of bone metastasis in 140 patients with lung cancer. For comparison, serum carcinoembryonic antigen (CEA), cytokeratin 19 fragment (CYFRA 21-1), gastr in-releasing peptide precursor (ProGRP), alkaline phosphatase and calcium w ere simultaneously measured. ICTP was measured by double-antibody radioimmu noassay. Results: ICTP was significantly higher in patients with bone metastasis fro m lung cancer than in the group without bone metastasis, patients with othe r pulmonary diseases or healthy control subjects and showed excellent sensi tivity and specificity, indicating that this marker is highly useful for co mplementary diagnosis of bone metastasis from lung cancer. Moreover, the su rvival duration was significantly shorter in the ICTP-positive group than i n the ICTP-negative group, suggesting that ICTP can be a prognostic factor in lung cancer. Conclusion: it is suggested that measurement of ICTP is worthwhile as a ser ological diagnostic method of bone metastasis from lung cancer. Moreover, s ince repeated measurements are possible, this measure was considered very h elpful in complementary diagnosis of bone metastasis and also as a standard to determine the timing of examinations such as bone scintigraphy.