Wait-and-See Treatment Strategy Could be Considered for Lung Adenocarcinoma with Special Pleural Dissemination Lesions, and Low Genomic Instability Correlates with Better Survival.

BACKGROUND: This study aimed to evaluate the feasibility of a wait-and-see strategy for non-small cell lung cancer (NSCLC) patients with special pleural dissemination lesions (r-pM1a and s-pM1a). Furthermore, the study characterized genomic alternations about disease progression. METHODS: For this study, 131 NSCLC patients with a diagnosis of pM1a were retrospectively selected. Survival differences were evaluated among patients treated with three different initial postoperative treatments: chemotherapy, targeted therapy, and wait-and-see strategy. Whole-exome sequencing (WES) was performed on primary and metastatic tumors of 10 patients with dramatic progression and 13 patients with gradual progression. RESULTS: The wait-and-see group showed better progression-free survival (PFS) than the chemotherapy group (p < 0.001) but PFS similar to that of targeted group (p = 0.984). This pattern persisted in epidermal growth factor receptor (EGFR)-positive patients. For patients with EGFR-negative/unknown status, PFS was longer in the wait-and-see group than in the two treatment groups. Furthermore, better overall survival (OS) was observed for the patients who received chemotherapy or targeted therapy after the wait-and-see strategy than for those who received chemotherapy or targeted therapy immediately. Lymph node status was an independent prognostic factor for PFS and OS. Finally, WES analysis showed that a high genomic instability index (GIS) and chromosome 18q loss were more common in metastatic tumors, and low GIS was significantly associated with better PFS (p = 0.016). CONCLUSIONS: The wait-and-see strategy could be considered for special pM1a patients without lymph nodes metastasis, and patients with a low GIS may be suitable for this strategy.