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Damjanov N , Meropol NJ
Oral therapy for colorectal cancer: How to choose
Oncology-New York. 2000 Jun;14(6) :799-807
PMID: ISI:000090129300005   
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Either alone or in combination with other antineoplastics, fluorouracil (5-FU) has been the mainstay of treatment of gastrointestinal, breast, and head and neck cancers for the past 40 years. Numerous active 5-FU schedules are in clinical use, but erratic oral bioavailability has historically mandated intravenous administration, Recently, two methods have been used to overcome the poor oral bioavailability of 5-FU. The first involves the use of prodrugs that are absorbed intact in the gastrointestinal tract and are ultimately converted to 5-FU in normal or turner tissues. An alternate approach involves the inhibition of gastrointestinal degradation via coadministration of an inhibitor of dihydropyrimidine dehydrogenase, the rate- limiting enzyme in 5-FU catabolism, The oral fluoropyrimidines currently in development result in prolonged exposure to 5-FU and, therefore, have the potential to achieve clinical benefits similar to those seen with protracted intravenous infusions of 5-FU, but without the cost, complications, and inconvenience of ambulatory infusion pumps. This review describes several oral fluoropyrimidine regimens with activity in colorectal cancer: capecitabine (Xeloda) tegafur, UFT, S-I, and eniluracil plus 5- FU. An understanding of the distinct mechanisms of action and toxicity patterns of each regimen may ultimately guide treatment selection when multiple choices become available.
Times Cited: 2 English Article 368QP ONCOLOGY-NY