To investigate the efficacy and safety of EGFR-TKI combined with thoracic radiotherapy as maintenance therapy in patients with advanced lung adenocarcinoma with positive EGFR mutation after induction therapy of EGFR-TKI.

Collecting the clinical characteristic of patients with advanced lung adenocarcinoma with positive EGFR mutation admitted to southwest Hospital of Army Military Medical University from January 2012 to July 2019, who received first-line EGFR-TKI treatment and achieved disease stability. Patients who underwent EGFR-TKI induction therapy to achieve disease stabilization and then maintained by thoracic radiotherapy were treated as the combined treatment group, maintained with monotherapeutic TKI were treated as the monotherapy group. Progression-free survival (PFS), duration of response (DOR), objective response rate (ORR), disease control rate(DCR)and adverse reactions of two groups were analyzed retrospectively.

A total of 178 patients met the criteria were collected, including 23 patients in the combined treatment group and 155 patients in the monotherapy group. 21 pairs were matched successfully after the propensity score matching at a ratio of 1︰1, Baselines of two groups of patients were consistent (P>0.05). Median PFS was 19.8 months in the combined treatment group and 12.3 months in the monotherapy group(P=0.000). The median DOR was 16.5 months and 9.8 months, respectively(P=0.002). ORR of two group was 85.7% and 76.2%(P=0.687). DOR were 100% in both groups.Grade 3 or worse adverse reactions were 5 cases (23.8%) and 4 cases (19.0%), respectively. The common adverse reactions of the two groups were not significantly different, and the most common was rash, 9 (42.8%) and 10 (47.6%) respectively. In the combined treatment group, there were 11 cases (52.4%) of radioactive pneumonia, including 10 cases of grade 1 and 1 case of grade 2.

After first-line EGFR-TKI induction therapy, EGFR-TKI combined with thoracic radiotherapy maintenance therapy showed better PFS benefit than EGFR-TKI single-drug maintenance therapy and the combination therapy group had a safety tolerance.