FP12.06 Solid Subtype Predicts Early Bone Metastases in Sensitive EGFR-Mutated Lung Adenocarcinoma Patients After Surgery

Abstract

Bone metastasis (BM) is common and associated with poor prognosis in NSCLC patients. However, valid predictors of BM remain insufficient. Solid pattern has been reported as a predictive factor in disease progression in resected NSCLC patients. This study aimed to explore the relationship between solid subtype and BM in EGFR-mutated lung adenocarcinoma patients after surgery. Patients with completely resected lung adenocarcinoma and sensitive EGFR mutation were included in our study. Patients with solid pattern were divided into solid-present group while the rest were in solid-absent group. CT (for chest and brain) was performed every 2-3 months. Bone scan was done every 4-6 months. BM was confirmed if one of the following criteria were fulfilled: (1) clinical or pathological confirmation of lung cancer and diagnosis of BM according to bone biopsy; or (2) pathologically diagnosed as lung cancer and with BM images. All patients received EGFR-TKI as the first-line treatment for progression after operation. Bone disease-free survival (bDFS), DFS and OS were assessed in this study. bDFS was defined as the time span between surgery and BM diagnosis. From January 2007 to January 2017, 237 eligible patients were identified. Among them, 81 patients (34.2 %) were solid-present. BM was observed in 94 patients (39.7 %). Solid-present patients had significantly shorter bDFS than solid-absent patients (14 months vs. 27 months; P < 0.001). The difference was still significant in patients with BM as first-site (12.5 months vs. 16.5 months; P = 0.016) and non-first-site progression (16.5 months vs. 45.5 months; P < 0.001) after surgery (Figure 1). In survival analysis, solid-present group showed a significantly shortened DFS (15 months vs. 19 months; P < 0.001) and OS (47 months vs. 77 months; P = 0.001) (Figure 2).View Large Image Figure ViewerDownload Hi-res image Download (PPT) These findings suggested that solid pattern predicted poor prognosis and early BM occurrence.