Ntavatzikos A, et al. – The effect of thymidylate synthase (TYMS), KRAS and BRAF were investigated in the survival of metastatic colorectal cancer (mCRC) patients treated with chemotherapy. In mCRC patients under fluoropyrimidine–based chemotherapy, the TYMS genotypes ins/ins and ins/loss of heterozygosity (LOH) correlated with worst prognosis.