Impact of EGFR tyrosine kinase inhibitors on skeletal-related events in EGFR mutation-positive non-small cell lung cancer patients with bone metastases.

Abstract

e18054 Background: Clinical outcome of EGFR mutation-positive non-small cell lung cancer (NSCLC) patients with bone metastases is less well known. The purpose of this study was to evaluate the clinical outcome of EGFR mutation-positive NSCLC patients with bone metastases who were treated with EGFR tyrosine kinase inhibitors (TKIs). Methods: From January 2008 to December 2010, 127 patients received first-line chemotherapy for advanced or postoperative recurrent NSCLC with bone metastasis at our institution. EGFR mutational status was analyzed using a PCR-based assay for EGFR exons 18 to 21. Clinical outcome including the incidence of skeletal-related events (SREs), time to the first SREs from first-line chemotherapy and overall survival (OS) was evaluated by the EGFR TKIs-sensitive mutations status (either exon 19 deletion or L858R in exon 21). SREs were defined as a pathologic fracture, spinal cord compression, surgery to bone, radiation therapy (RT) to bone, other radiological intervention, and hypercalcemia of malignancy. Results: Sixty-two (50%) of the 125 patients were sensitive EGFR mutations positive. 39 of 62 (63%) EGFR mutation-positive patients were treated with EGFR TKIs (gefitinib or erlotinib) as first-line chemotherapy, and most of negative patients received cytotoxic agents such as platinum-based chemotherapy. Zoledronic acid were administered in 50 % of EGFR mutation-positive patients, and in 57 % of negative patients, respectively (P= 0.59). With a median follow-up of 13 months, the incidence of SREs were 21% in EGFR mutation-positive patients, and 38% in negative patients, respectively (P<0.05). Additionally, median time to first SREs from first-line chemotherapy in EGFR mutation-positive patients was significantly longer than negative patients (13 months versus 6 months, P<0.05). Median OS in mutation-positive patients was 26 months, as opposed to 12 months in negative patients (P<0.05). Conclusions: Our study indicated that EGFR mutation-positive NSCLC patients with bone metastases who were treated with EGFR TKIs have favorable clinical outcome on SREs compared with mutation-negative patients.