Association Between Oligo-Residual Disease and Patterns of Failure During EGFR-TKI Treatment in EGFR-Mutated Non-Small Cell Lung Cancer: A Retrospective Study

Background: Local ablative therapy (LAT) may be beneficial for patients with epidermal growth factor receptor ( EGFR ) mutated non-small cell lung cancer (NSCLC) with oligo-residual disease after treatment with EGFR tyrosine kinase inhibitor (EGFR-TKI). However, this has not been fully established. This study aimed to evaluate the predominant progressive disease (PD) pattern limited to residual sites of disease after treatment with EGFR-TKI. Methods: Patients with advanced EGFR -mutated NSCLC treated with EGFR-TKIs as first-line therapy were retrospectively analysed during a 7-year period. Oligo-residual disease was defined as the presence of 1 – 4 lesions (including the primary site) at 3 months from the start of EGFR-TKI treatment. The predictive factors of PD patterns after EGFR-TKI treatment were evaluated. Results: A total of 207 patients were included. Three months after the start of EGFR-TKI treatment, 66 patients (32%) had oligo-residual disease. A total of 191 patients had PD, 60 with oligo-residual disease and 131 with non-oligo-residual disease. Regarding the pattern, 44 patients (73%) with oligo-residual disease and 37 patients (28%) with non-oligo-residual disease had PD limited to the residual sites. Multivariate logistic regression analysis at 3 months from the start of EGFR-TKI treatment revealed that oligo-residual disease ( P < 0.001), the lack of residual central nervous system metastases ( P = 0.032), and initial treatment with osimertinib ( P = 0.028) were independent predictors of PD limited to residual disease sites. Conclusions: This study provided a rationale for LAT to all sites of residual disease in patients with oligo-residual disease during EGFR-TKI treatment.