Although there is a published clinical pilot study of the FLT “flare” in NSCLC which did not demonstrate a predictive value of this technique [20], it is plausible that other variables such as concurrent treatment with dexamethasone, known to decrease the expression of thymidylate synthase and dihydrofolate reductase and impact tumor responsiveness to pemetrexed [26], could impact the translation of this technique into the clinic. This evidence concerns the gene DHFR and neoplasm.