Incidence, prognostic factors, and a nomogram of lung cancer with bone metastasis at initial diagnosis: a population-based study.

Background: Bone is one of the common metastatic sites of lung cancer, and its prognosis is not optimistic. We performed a study to evaluate the incidence, survival, and prognostic factors of lung cancer with bone metastasis (LCBM) at initial diagnosis, and to develop a nomogram to predict its outcomes.

Methods: We conducted a retrospective study choosing 13,541 patients with LCBM from the Surveillance, Epidemiology, and End Results (SEER) 18 registry database. An X-tile analysis provided the optimal age cutoff point. The incidence, overall survival, and prognosis of bone metastasis were evaluated according to the patient information, characteristics of the tumor, and therapy. We also used multivariable Cox regression to estimate mortality hazard ratios (HRs) among patients with LCBM, while a visual nomogram was established to judge the prognosis.

Results: The incidence of disease increased with age, but survival rates show the opposite trend. The median survival time was about 4 months. In addition, although the differences for patient race is not significant (P=0.445), White patients are prone to have bone metastases from lung cancer according to the incidence analysis. The difference for laterality is also not significant (P=0.534), while the factors of age, gender, the total number of sites, histological types, grade, tumor size, and treatment are significantly related to the outcome of patients with LCBM. Furthermore, our nomogram could predict the probability of surviving to the median survival time of the population with a c-index of 0.72.

Conclusions: Age, characteristics of the tumor, and therapy should be considered for prediction of prognosis for patients with lung cancer bone metastasis. Putatively, the younger patients and the patients with chemotherapy and surgery may indicate improved survival.