Spine-specific skeletal related events and mortality in non-small cell lung cancer patients: a single-institution analysis

Abstract

Objective: The population prevalence of non-small cell lung cancer (NSCLC) continues to increase; however, data are limited regarding the incidence rate of skeletal related events (SREs) (i.e., surgery to the spinal column, radiation to the spinal column, radiofrequency ablation, kyphoplasty/vertebroplasty, spinal cord compression, or pathological vertebral body fractures) and their impact on overall mortality. In this study, the authors sought to estimate the incidence rates of SREs in NSCLC patients and to quantify their impact on overall mortality.

Methods: This was a single-institution retrospective study of patients diagnosed with NSCLC between 2002 and 2014. The incidence rates for bone metastasis and subsequent SREs (per 1000 person-years) by time since lung cancer diagnosis were calculated and analyses were stratified separately for each histological type. Incidence rates for mortality at 1, 2, and 3 years from diagnosis stratified by the presence of SREs were also calculated. Kaplan-Meier survival curves were constructed to describe crude survival ratios in patients with spine metastasis and SREs and those with spine metastasis but without SREs. These curves were used to estimate the 1- and 2-year survival rates for each cohort.

Results: We identified 320 patients with incident NSCLC (median follow-up 9.5 months). The mean ± SD age was 60.65 ± 11.26 years; 94.48% of patients were smokers and 60.12% had a family history of cancer. The majority of first-time SREs were pathological vertebral body compression fractures (77.00%), followed by radiation (35%), surgery (14%), and spinal cord compression (13.04%). Mortality rates were highest in NSCLC patients with spine metastasis who had at least 1 SRE. Stratifying by histological subtype, the incidence rate of mortality in patients with SRE was highest in the large cell cohort, 7.42 per 1000 person-years (95% CI 3.09-17.84 per 1000 person-years); followed by the squamous cell cohort, 2.49 per 1000 person-years (95% CI 1.87-3.32 per 1000 person-years); and lowest in the adenocarcinoma cohort, 1.68 per 1000 person-years (95% CI 1.46-1.94 per 1000 person-years). Surgery for decompression of neural structures and stabilization of the spinal column was required in 6% of patients.

Conclusions: SREs in NSCLC patients with bone metastasis are associated with an increased incidence rate of mortality.

Keywords: bone metastases; lung cancer; non–small cell lung; oncology; pathologic compression fracture; skeletal related events; spinal cord compression; spine.