DHFR and non-small cell lung carcinoma: In summary, we performed a systematic genetic association study of 16 SNPs in 7 selected genes (SLC19A1, FPGS, MTHFR, DHFR, GGH, ATIC, and TS) and therapeutic responses of pemetrexed-based treatment (ADRs and therapeutic effects) using 203 Han Chinese patients with advanced NSCLC.