P3.02b-059 The Role of Epidermal Growth Factor Receptor in the Onset of Skeletal Related Events in Non-Small Cell Lung Cancer: Topic: EGFR Clinical

Abstract

Bone metastasis is frequent in non-small cell lung cancer (NSCLC) patients, and subsequent skeletal related events (SREs) adversely deteriorate life quality and survival. Patients harboring sensitive epidermal growth factor receptor (EGFR) mutation experience a prolonged life expectancy. However, it is unclear whether survival enhancement in NSCLC patients with sensitive EGFR mutation may encounter an increase in the onset of SREs or not. Also, it is still unknown whether time to SREs is impacted by EGFR mutation status. In this study, we evaluated the impact of EGFR mutation status and other clinic-pathological variables on the incidence of SREs and on survival outcomes of SREs in stage IV NSCLC patients. We conducted a retrospective study of medical records from patients who were diagnosed stage IV NSCLC in a single institute. EGFR mutation status, and other clinical-pathological variables, bone metastasis outcomes and survival data were collected and statistically analyzed. 410 patients with evident bone metastasis were enrolled in the study. 49.0% patients were detected with sensitive EGFR mutation, and 29.0% were prophylactically administered bisphosphonate. 42.7% experienced at least one SRE, the most common type of which was palliative radiotherapy. Patient harboring sensitive EGFR mutation hold a lower incidence of SREs than patients who were detected with wild type EGFR (37.3% vs 47.8%, p=0.031), and patients who received bisphosphonate confronted a lower incidence of SRE comparing with patients who didn’t receive bisphosphonate prophylactically (36.1% vs 45.4%, p=0.087). Median time from bone metastasis to first SRE was two months longer in patients with EGFR mutation, comparing to patients with wild type EGFR, with a marginal significance (5.0m vs 3.0m, p=0.08). The administration of bisphosphonate delayed the median time to first SRE for 5 months (7.0m vs 2.0m, p=0.037). In multivariate analysis using a Cox proportion model, wild type EGFR (HR=1.559, 95% CI 1.081-2.249), multiple bone lesions (HR=1.991, 95% CI 1.217-3.258), mixed type bone lesions (HR=2.144, 95% CI 1.085-4.238) were independent risk factors of survival post first SRE, while a smoking history (HR=1.428, p=0.053) was shown marginally significant with an impaired survival post first SRE. This retrospective study shows that EGFR mutation has a propensity to impact the onset of SRE and prolong survival post first SRE in patients with stage IV NSCLC. For patients with higher risks to experience SREs, bisphosphonate is an alternative to impede the process.