Diagnostic and prognostic validity of serum bone turnover markers in bone metastatic non-small cell lung cancer patients

The incidence of bone metastases (BM) in advanced non-smallcell lung cancer (NSCLC) patients is estimated to range from 30% to 40% [1,2]. The presence of BM often results in pathologic remodeling of the affected bone compartment, making affected bones vulnerable to skeletal related events (SREs). SREs include pathologic fractures, spinal cord compression, requirement for radiation, surgery to bone and hypercalcemia, all reducing quality of life and worsening prognosis [3]. BM is a poor prognostic survival factor [4]. Therefore, early diagnosis and adequate treatment of BM is critically important issues of the clinical management of NSCLC patients. To detect BM in NSCLC patients, bone scintigraphy combined with plain radiographs, computerized tomography (CT) and magnetic resonance imaging (MRI) is recommended. But routine radiography only gives definite diagnosis when the bone is already substantially damaged by the tumor. Although scintigraphy is more sensitive, its specificity is not satisfactory due to pseudopositive values caused by inflammation and traumatic fracture. Any abnormal scintigraphic findings should always be verified by radiographic ones [5]. Bone scintigraphy is also a more expensive, invasive, time-consuming, and exposes cancer patients to irradiation, limiting its use for monitoring purposes. Since BM impairs the balance between bone formation and bone resorption, altered bone remodeling activities can be assessed directly by measuring the components of affected bone