Risk factors for skeletal-related events (SREs) and factors affecting SRE-free survival for nonsmall cell lung cancer patients with bone metastases

Skeletal-related events (SREs) for nonsmall cell lung cancer (NSCLC) patients with bone metastasis lead to serious morbidity. The aim of this study was to determine risk factors for SREs in NSCLC patients with bone metastasis and the factors influencing SRE-free survival and overall survival (OS). From 2000 to 2012, we evaluated retrospectively 835 NSCLC patients. Three hundred and thirty-five of them with bone metastasis were included in the study. SREs and the other prognostic factors were evaluated by univariate and multivariate analysis for SRE-free survival and OS. SREs were detected in 244 patients (72.8 %). The most common SREs were the need for radiotherapy (43.2 %) and malignant hypercalcemia (17.6 %). The median time to first SRE was 3.5 months at the median follow-up of 17 months. A multivariate analysis showed that the presence of bone metastasis at diagnosis (p < 0.001), the number of bone metastasis (p = 0.001), baseline hypercalcemia (p = 0.004), and the presence of palliative radiotherapy (p = 0.04) were independent prognostic factors for SRE-free survival. A logistic regression analysis identified that the presence of bone metastasis at diagnosis [odds ratio (OR), 12.6], number of bone metastasis (OR, 3.05), and baseline hypercalcemia (OR, 0.33) were found to be predictive factors in the developing of SRE. The median OS time for patients with SRE was worse than that for patients without SRE (7 vs 12 months, respectively). For OS, male gender, ECOG performance status (PS), high lactate dehydrogenase (LDH) level, hypoalbuminemia, the presence of bone metastasis at diagnosis, the number of bone metastasis, the presence of SREs, the presence of bisphosphonate therapy, and palliative radiotherapy were independent prognostic indicators for OS by the multivariate analysis. Our results indicated that the frequency of SREs was high and the presence of bone metastasis at the time of diagnosis, baseline hypercalcemia, and multiple bone metastases were significant factors predicting the occurrence of SREs. If bone metastases diagnose earlier, treatments for the prevention of SREs may be initiated earlier; thus, the deterioration of quality of life may be preserved.