P3.16-013 Prognostic Effect of EGFR Gene Mutation for Recurrence in Completely Resected Lung Adenocarcinoma

Abstract

Prognostic effect of EGFR gene mutation in disease progression which affecting recurrence pattern and recurrence dynamics after complete resection of lung adenocarcinoma has not been well established. We investigated the relationship between EGFR gene mutation and recurrence dynamics in completely resected lung adenocarcinoma. We retrospectively review 527 patients who underwent curative surgery for lung adenocarcinoma from January 2006 to December 2009. Demographics, clinic-pathologic data, and prognosis data were obtained by review of medical records. The EGFR gene mutation was analyzed by nested polymerase chain reaction followed by bidirectional direct sequencing in case of recurrence. Adenocarcinoma patients who experienced recurrence and had data of EGFR mutation were included in the analysis. Pathologic stage IV were excluded. Patients were divided into M group (mutant EFGR gene) or W group (wild-type EGFR gene). Sites of recurrence and disease-free times (DFT) of two groups were compared. Median follow-up duration was 72 months. Overall 5-year survival rate was 80.1%. Recurrence was detected in 153 patients and 5-year disease-free rate was 58.2%. EGFR gene sequencing was performed in 118 (77.1%) patients. There were 38 (32.2%) loco-regional recurrences and 80 (67.8%) distant metastases. Any mutation of EGFR gene was detected in 66 (59.9%) patients (M group) and 52 patients had wild-type EGFR gene (W group). Sites of recurrence in M group were loco-regional in 25 (37.9%) and distant metastasis in 41 (62.1%) patients. Site of recurrence in W group were loco-regional in 13 (25%) and distant metastasis in 39 (75%) patients. Sites of recurrence of both groups were not significantly different. (p=0.14) Median DFT of two groups were significantly different (M = 20.3 months vs W = 15.1 months, p=0.039). Visceral pleura invasion (p=0.045) and EGFR gene mutation (p=0.039) were prognostic factor for DFT in univariable analysis. In multivariable analysis, EGFR gene mutation was the only prognostic factor for DFT. (HR – 0.676, 95% CI – 0.371 ∼ 0.986, p=0.042) No significant factor for DFT was identified in loco-regional recurrence. EGFR gene mutation, however, was the only significant prognostic factor for DFT of distant metastasis (HR – 0.561, 95% CI – 0.356 ∼ 0.885, p=0.013) in univariable and multivariable analysis. In recurrent lung adenocarcinoma, EGFR gene mutation group showed longer DFT than wild-type EGFR group. EGFR gene mutation is a prognostic factor in lung adenocarcinoma and slow-growing nature of adenocarcinoma with EGFR gene mutation should be considered in surveillance after surgery.