Effect of postoperative systemic therapy on pulmonary adenocarcinoma with unexpected pleural spread detected during thoracotomy or thoracoscopy

Background: Occasionally, malignant pleural disease is only detected unexpectedly during surgery in patients with pulmonary adenocarcinoma. Previous studies mostly focused on the role of main tumor resection on patient's outcome, barely addressing the position of postoperative systemic therapy. Methods: The medical records of 5321 non-small cell lung cancer patients who underwent thoracic surgery between January 1990 and December 2012 were reviewed. Pulmonary adenocarcinoma patients with unexpected pleural spread noted during surgery were included. The clinical and postoperative treatment variables were assessed for correlation with overall survival. Results: In 134 patients identified, main tumor resection was performed in 87 (64.9%) patients, while 89 (66.4%) and 57 (42.5%) patients received postoperative chemotherapy and epidermal growth factor receptor- tyrosine kinase inhibitor (EGFR -TKI) therapy, respectively. Overall, the 5-year survival rate was 30.2% and median survival time was 29.3 months. Multivariate analysis showed main tumor resection and EGFR-TKI therapy were associated with better survival. Mutational status of EGFR was available in 57 patients and 43 (75.4%) had activating mutations. Resection of the main tumor conferred a better outcome in patients without EGFR mutation or with unknown EGFR mutation status and had not been treated with EGFR-TKI therapy (P = 0.003), but not in those with activating EGFR mutation and had been treated with EGFR-TKI (P = 0.857). Conclusions: In pulmonary adenocarcinoma patients with unexpected pleural spread detected during surgery, main tumor resection and EGFR-TKI therapy correlated with better survival. Identifying EGFR mutation status before surgery can provide useful information for clinical decision during surgery.