Molecular Risk Stratification is Independent of EGFR Mutation Status in Identifying Early-Stage Non-Squamous Non-Small Cell Lung Cancer Patients at Risk for Recurrence and Likely to Benefit From Adjuvant Chemotherapy.

BACKGROUND A clinically-certified gene expression profile improved survival in a cohort of stage I-IIA NSCLC patients by identifying those likely to benefit from adjuvant intervention. EGFR mutation status has not provided this type of predictive risk discrimination in stage IA NSCLC, and overtreatment of low-risk stage IB patients may have limited the overall benefit seen recently in the adjuvant application of a third-generation TKI. We compared EGFR mutation data to molecular risk stratification in a prospective, early-stage cohort. MATERIALS AND METHODS Two hundred fifty eligible stage I-IIA non-squamous NSCLC patients underwent prospective molecular risk stratification by the 14-gene prognostic assay. Platinum doublet adjuvant chemotherapy (AC) was recommended for molecular high-risk (MHR). Differences in freedom from recurrence (FFR) and disease-free survival (DFS) were evaluated. RESULTS At 29 months, prospective molecular testing yielded an estimated FFR of 94.6% and 72.4% in low-risk and untreated MHR patients, respectively, and 97.0% among MHR patients receiving AC (P < .001). In contrast, there was no association between EGFR status and recurrence, while molecular risk predicted survival and response to AC within both the EGFR mutation(+) and mutation(-) populations. Sixty-seven percent of EGFR(+) and 49% of EGFR(-) patients were molecular low-risk. CONCLUSION This prospective study demonstrates the utility of the 14-gene assay independent of EGFR mutation. Basing adjuvant intervention in early-stage NSCLC on EGFR status alone may undertreat up to 51% of EGFR(-) patients likely to benefit from adjuvant intervention, and overtreat as many as 67% of EGFR(+) patients more likely to be free of residual disease.