EGFR gene mutation is not a significant prognostic factor in patients with EGFR mutated non-small cell lung cancer who receive best supportive care alone.

Abstract

e21736 Background: Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), are less toxic than conventional chemotherapy drugs, and benefit patients with EGFR-mutated non-small cell lung (NSCLC) cancer. However, there are a few patients who are not able to receive EGFR-TKI due to poor performance status, older age, or sever comorbidities. Here, we aimed to determine the prognostic significance of EGFR mutation in NSCLC patients who received best supportive care (BSC) alone, and compare the anti-tumor outcomes of only EGFR-TKI-treated patients vs. BSC patients. Methods: We retrospectively reviewed the medical records of patients diagnosed with NSCLC at Higashihiroshima Medical Center during April 1991–January 2019 and Hiroshima University Hospital during April 2008–August 2018. Results: A total of 1163 patients diagnosed with unresectable NSCLC were included in this analysis. Of these 1163 patients, 234 patients received BSC alone.Among 196 patients who underwent EGFR mutation analysis, 38 and 158 did and did not harbor an EGFR mutation, respectively, and the mean survival times (MST) did not differ significantly between these groups (121 vs. 85 days, p = 0.789). Consistent with the survival analysis, the multivariate Cox regression analyses showed EGFR mutation was not an independent prognostic factor. After propensity score matching, a comparison of only EGFR-TKI-treated (n = 35) and BSC patients (n = 35) with EGFR mutation revealed that the former had a significantly longer MST than the latter (372 vs. 121, p < 0.001). Conclusions: EGFR mutation itself was not a significant prognostic factor in untreated NSCLC patients. The patients who received EGFR-TKI had a significantly longer MST than their untreated counterparts. Our results may help to explain the benefit of EGFR-TKI, particularly for patients who would be directed towards treatment with BSC.