The bone resorption biomarkers urinary NTx (uNTx) and serum NTx (sNTx) have been shown to aid in the diagnosis of bone metastasis in patients with lung cancer. Patients with metastatic bone disease from lung cancer (MBDLC) are often treated with zoledronic acid. Zoledronic acid reduces the levels of bone resorption biomarkers and also the risk of skeletal adverse events in patients with MBDLC. We studied the effects of treatments including zoledronic acid on levels of sNTx during disease progression.Methods
Patients with MBDLC at the initial diagnosis were entered to this study. sNTx was measured once a month using the sNTx assay OSTEOMARKTM serum NTx (Alere Medical). MBDLC was characterized by monthly physical examination and by bone scintigraphy every 3 months for 12 months. All patients were required to provide written informed consent.Results
Twenty patients were enrolled between June and December 2010. The mean ± 1 SD of the sNTx concentrations was 19.8 ± 5.8 nM BCE/L at baseline. In the 16 patients receiving zoledronic acid, the levels of sNTx showed a significant decrease in the first month of treatment (baseline: 21.3 ± 5.5 nM BCE/L; one month later: 13.6 ± 2.7 nM BCE/L; P < 0.01). During follow-up period, 12 of the patients treated with zoledronic acid experienced worsening MBDLC or had died from lung cancer, and there were statistically significant differences in the levels of sNTx at baseline (19.7 ± 4.47 nM BCE/L), at the lowest levels after the administration of zoledronic acid (11.5 ± 2.73 nM BCE/L) and at the point of measurable disease progression or death (13.0 ± 2.07 nM BCE/L).Conclusions
Serial measurements of sNTx in patients with MBDLC treated with zoledronic acid might predict disease progression of bone metastasis. Administration of zoledronic acid significantly decreased the level of sNTx from baseline within one month and maintained the level of sNTx lower than baseline during study periods.