Comparing the OS of different second-line chemotherapy regimens, pemetrexed was associated with better OS than was vinorelbine in gefitinib users with advanced EGFR mutant lung adenocarcinoma (Ref: pemetrexed, HR: 1.65, 95% CI: 1.28–2.13, p = 0.0001) (Table 2). Here, EGFR is linked to lung adenocarcinoma.