Diagnosis of bone metastasis in patients with lung cancer using urinary and serum collagen type I telopeptide (NTx).

Abstract

e18044 Background: Many cancers metastasize to bone. Bone metastasis may cause an increase in bone resorption due to direct effects of the tumor itself or osteoclastic activation. This study evaluates the bone resorption biomarkers urinary NTx (uNTx) and serum NTx (sNTx) for the diagnosis of bone metastasis in patients with lung cancer. Methods: uNTx and sNTx were measured in 100 patients with lung cancer and 50 control patients with benign respiratory diseases using the uNTx:OSTEOMARKTM and sNTx:OSTEOMARKTM serum NTx assays (Inverness Medical Japan). Bone metastasis was characterized by scintigraphy. The extent of disease (EOD) was determined by the number of sites of bone metastasis. Area under the curve (AUC) for receiver operating characteristic (ROC) analysis was used to evaluate the detection of bone metastasis. Sensitivity and specificity of uNTx and sNTx to detect bone metastasis were calculated using cutpoints of 64 nM BCE/mM Cr for uNTx and 22 nM BCE/mM Cr for sNTx. All patients were required to provide written informed consent. Results: Patients with bone metastasis had significantly higher levels of both uNTx and sNTx (uNTx; 93.2 +/- 105.1 nM BCE/mM Cr., sNTx; 24.0 +/- 14.6 nM BCE/L) vs. lung cancers without bone metastasis (uNTx; 51.6 +/- 26.8 nM BCE/mM Cr., sNTx;17.2 +/- 4.1 nM BCE/L), or benign respiratory diseases (uNTx; 42.8 +/- 21.8 nM BCE/mM Cr., sNTx; 16.8 +/- 7.9 nM BCE/mM Cr.). There was good correlation between uNTx and sNTx (R = 0.807). ROC AUC for the detection of bone metastasis was 0.743 for uNTx and 0.712 for sNTx. The sensitivity and specificity for the diagnosis of bone metastasis using uNTx was 48.0% and 86.0%, and using sNTx was 40.0% and 87.0%, respectively. Levels of uNTx and sNTx were increased in patients classified as EOD grade 1 compared to controls and in patients classified as EOD grade 2 or greater, compared to patients classified as EOD grade 1. Conclusions: Both biomarkers may have value as an aid in the diagnosis of bone metastasis in patients with lung cancer.