Introduction: Adjuvant radiotherapy in non–small-cell lung cancer (NSCLC) remains controversial,Whether the mutation status of epidermal growth factor receptor (EGFR) will affect the recurrence and survival of patients with resected NSCLC is rarely reported. Our purpose is to study the effect of postoperative radiotherapy on patients with stage IIIA(N2) NSCLC with EGFR mutation.
Methods: Total of of 115 patients diagnosed with stage IIIA(N2) resected NSCLC were analyzed retrospectively. Their EGFR mutations were detected by real-time quantitative PCR and DNA sequencing technology together.
Results: At a median follow-up of 34.2 months for the postoperative adjuvant radiotherapy (PORT) group and 31.0 months for the non-PORT group, PORT group significantly improved progression free survival (PFS) and overall survival (OS). The median PFS and OS in the EGFR mutant group were not significantly longer than those in the EGFR wild-type group. The number of chemotherapy cycles, postoperative radiotherapy and the number of metastatic lymph nodes were independent factors influencing long-term survival.
Conclusion: Our retrospective analysis showed that PORT can improve survival of patients with stage IIIA(N2) NSCLC. EGFR-mutant group with stage IIIA(N2) NSCLC has a tendency of a higher survival than the wild-type EGFR group, but there was no significant difference for both groups. The EGFR mutation status was not associated with PFS or OS of stage IIIA(N2) NSCLC.

Keywords: non-small cell lung cancer, N2-stage, adjuvant radiotherapy, EGFR mutations

INTRODUCTION

Despite advances in treatment, lung cancer remains the leading cause of cancer-related deaths in humans. Approximately 25–30% of non-small-cell lung cancer (NSCLC) patients are diagnosed at a locally advanced stage (IIIA or IIIB), and postoperative 5-year survival rates range from 13% to 42.8%.^1–3 Based on several prospective clinical trials that have validated the survival benefit of concurrent chemoradiotherapy over radiotherapy alone⁴ or chemotherapy followed by sequential radiotherapy for stage IIIA (N2) NSCLC.^5,6 However, stage IIIA (N2) NSCLC patients have heterogeneous disease presentation,⁷ the value of postoperative adjuvant radiotherapy(PORT) for completely resected NSCLC remains controversial, as the effect on survival has been inconclusive.^8–10 A secondary analysis of a prospective trial illustrated the benefit of adding PORT in pN2 disease regardless of chemotherapy use,¹¹ this has been supported by multiple high-volume retrospective investigations.¹² Furthermore, whether epidermal growth factor receptor (EGFR) mutation is associated with long-term survival in patients with Completely Resected Pathologic IIIA(N2) NSCLC is unclear. The purpose of this study was to explore the relationship between EGFR mutation status and long-term survival with combined chemoradiation.

METHODS AND MATERIALS

Patient selection

One hundred and fifteen stage with pathological stage IIIA(N2) NSCLC were surgically treated at the Shandong Cancer Hospital and Institute (Jinan, China) between March 2011 and December 2015 were retrospectively reviewed. Histology and fluorodeoxyglucose positron emission tomography computed tomography (FDG-PET/CT) confirmed the staging of all patients. The median follow-up time was 34.2 months (range 3.5–42.7 months).

Each patient received postoperative adjuvant chemotherapy. The inclusion criteria for the postoperative radiotherapy and chemotherapy group (PORCT) groups and the postoperative chemotherapy group (POCT) groups were the same, as follows: complete surgical resection through either lobectomy or pneumonectomy; systematic nodal dissection, a minimum of three N2 stations sampled or complete dissection (one of which must be the subcarinal station); and histologically proven NSCLC of stage pT1-3N2M0 (according to the TNM classification in the UICC 7th ed).^13,14 Patients who received neoadjuvant therapy (chemotherapy and/or radiotherapy), showed evidence of metastatic disease or presented with previous malignancy were excluded. Patients with EGFR mutations receiving tyrosine kinase inhibitor (TKI) treatment after surgery were also excluded. Then, the EGFR mutational states of the two groups were compared.

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