CDA and cancer: Capecitabine is an oral form of fluoropyrimidine prodrug that is metabolized to 5-fluorouracil (5FU) in three steps [3,4]; initially, capecitabine is hydrolyzed by carboxylesterase to form 5 deoxyfluorocytidine, which then undergoes a second metabolism by cytidine deaminase to produce 5 deoxy-5 fluorouridine, which is considered to be active in cancer cells as well as liver cells [3,4].