Spontaneous osteoclastogenesis is a predictive factor for bone metastases from non-small cell lung cancer

Lung cancer is a widespread disease and its incidence is growing. Since therapies have increased the life expectancy of lung cancer patients, the development of bone osteolytic metastases is becoming a common cause of morbidity. Osteolysis is caused by an increased osteoclast activity and may be reduced by inhibiting their formation and activity. We studied 60 male patients affected by NSCLC, divided in early and advanced stage disease. Patients' blood and urinary samples were collected at tumor diagnosis and at follow-up. PBMCs were cultured to investigate the spontaneous osteoclastogenesis. IL-7 was dosed in serum and its quantitative gene expression was evaluated on tumor and healthy tissues by RQ-PCR. Both at diagnosis and follow-up, osteolytic bone patients showed high spontaneous osteoclastogenesis level compared to non-bone metastatic and healthy controls. The presence of spontaneous osteoclastogenesis correlated with urinary crosslinks increase. Serum IL-7 levels were higher in bone metastatic patients than in patients without bone lesions and healthy controls. The serum IL-7 increase correlated with the osteoclastogenesis and, at least in part, depended on an increased IL-7 production by tumor cells. At follow-up, patients with increased osteoclastogenesis and serum IL-7 levels, were subjected to standard clinical analysis, which showed early secondary bone lesions. The in vitro assay for spontaneous osteoclastogenesis and serum IL-7 dosage could be useful for diagnostic purposes and it might be able to monitor cancer patients with a high risk to develop osteolytic metastases at follow-up, especially after a curative treatment.