Efficacy of adjuvant chemotherapy in stage II/III NSCLC with EGFR mutation.

BACKGROUND: Adjuvant cisplatin-based chemotherapy improves the survival of patients with resected pathological stage II/III non-small cell lung cancer (NSCLC). However, the efficacy in patients with epidermal growth factor receptor (EGFR) mutations remains controversial.

METHODS: This retrospective study included 353 patients with resected pathological N1/N2 stage II/III NSCLC between 2010 and 2016. Mutant EGFR (mEGFR) was detected in 76 patients. Adjuvant chemotherapy (AC) was administered to 151 patients. We compared cancer-specific survival (CSS) and recurrence-free survival (RFS) between AC and surgery alone (SA) groups, including patients with wild-type EGFR (wEGFR) and mEGFR. Using multivariate analysis, we evaluated the prognostic factors in patients with wEGFR and mEGFR.

RESULTS: The median follow-up time was 4.7 y. In patients with wEGFR, the differences in CSS and RFS between the AC (n=114) and SA (n=163) groups were significant (CSS: 66.8% [5 y] versus 49.4% [5 y], p=0.001; RFS: 54.2% [5 y] versus 39.2% [5 y], p=0.013). The significant prognostic factors were AC (versus SA; p<0.0001), % DLco>60% (p=0.028), tumor size (p<0.001), lymphatic permeation (p=0.041), and pN1 (versus pN2) [p<0.001]. However, the differences in CSS and RFS between the AC (n=37) and SA (n=39) groups were not significant (CSS: 64.0% [5 y] versus 58.1% [5 y], p=0.065; RFS: 45.0% [5 y] versus 33.8% [5 y], p=0.302). Multivariate analysis identified no significant prognostic factors in patients with mEGFR.

CONCLUSIONS: We demonstrated the efficacy of AC in patients with mEGFR and wEGFR. The efficacy of AC may be lower in patients with mEGFR than in those with wEGFR.