Serum COX-2 levels were measured in patients in the D-TORCH study's experimental and placebo arms at baseline and 12 weeks of capecitabine-based therapy or at the development of HFS (whichever occurred earlier) and in 20 age-matched healthy controls using a human COX-2 ELISA kit (E-EL-H5574). This evidence concerns the gene PTGS2 and Hand-foot syndrome.