Local microwave ablation with continued EGFR tyrosine kinase inhibitor as a treatment strategy in advanced non-small cell lung cancers that developed extra-central nervous system oligoprogressive disease during EGFR tyrosine kinase inhibitor treatment: A pilot study

The non-small cell lung cancer (NSCLC) patients that experienced good clinical response to epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKIs) will ultimately develop acquired resistance. This retrospective study was performed to explore the potential survival benefit of microwave ablation (MWA) therapy in epidermal growth factor receptor (EGFR)-mutant NSCLC that developed extra-central nervous system (CNS) oligoprogressive disease during TKI treatment. We retrospectively analyzed 54 NSCLC patients with EGFR mutations who showed a clinical benefit from initial EGFR-TKI therapy and developed extra-CNS oligoprogressive disease at our institutions. Twenty eight patients received MWA as a local therapy for the metastatic sites and continued on the same TKIs (MWA group). The following 26 patients received systemic chemotherapy after progression (chemotherapy group). The progression-free survival (PFS1) was calculated from initiation of targeted therapy to first progression. Progression-free survival (PFS2) was defined from first progression to second progression after MWA or chemotherapy. Overall survival (OS) was calculated from the time of diagnosis to the date of last follow-up or death. The median PFS1 for both groups was similar (median 12.6 vs. 12.9 months, HR 0.63). However, the MWA group patients had a significantly longer PFS2 (median 8.8 vs. 5.8 months, hazards ratio [HR] 0.357) and better OS (median 27.7 vs. 20.0, HR 0.238) in comparison with chemotherapy group. Multivariate analysis and the internal validation identified MWA as the main favorable prognostic factor for PFS2 and OS. In the MWA group, the median PFS2 for complete ablation was significantly longer than that for incomplete ablation (11 vs. 4.2 months, HR 0.29, P < 0.05). MWA with continued EGFR inhibition might be associated with favorable progression-free survival (PFS) and OS in patients with extra-CNS oligometastatic disease. MWA as a local therapy for extra-CNS oligometastatic disease should be considered for NSCLC with acquired resistance to EGFR-TKIs.