Risk factors for skeletal-related events in patients with non-small cell lung cancer treated by chemotherapy

The purpose of this study was to identify the risk factors for skeletal-related events (SREs) in patients with advanced non-small cell lung cancer (NSCLC). SREs were defined as pathologic fractures, spinal cord compression, requirement for radiation therapy, other radiological intervention, or surgery to the bone, and hypercalcemia of malignancy. Time-to-the first SRE and SRE-free survival, and their associations with the patient characteristics were evaluated retrospectively in 642 patients with metastatic NSCLC who received systemic chemotherapy. A total of 118 (18.4%) patients developed SREs during or after the initial chemotherapy. Of these, 107 required radiotherapy to the bone, 5 developed hypercalcemia of malignancy, 3 developed compression fracture of the vertebrae, 2 required surgical treatment of the bone, and 1 underwent radiofrequency ablation therapy to the bone. The first SRE occurred within 12 months in 80 (67.8%) of the 107 patients. The results of multivariate analysis revealed that male sex, performance status (PS) of 2-3 and multiple bone metastases were risk factors for the first SRE, with hazard ratios (HRs) (95% confidence interval [CI]) to the reference of 1.44 (0.98-2.11), 2.21 (0.97-5.03) and 4.43 (2.91-6.76), respectively. SRE-free survival showed a similar trend. The HRs (CI) of male sex, PS of 2 and multiple bone metastases were 1.64 (1.30-2.06), 3.72 (2.31-5.98) and 1.80 (1.40-2.31), respectively. In conclusion, the presence of multiple bone metastases was significantly associated with the development of SRE in patients with advanced NSCLC treated by systemic chemotherapy. Male sex and poor performance status may be additional risk factors for the development of SREs in these patients.