Leucovorin modulation of fluorouracil in advanced colorectal cancer. T
he rational of leucovorin modulation of 5-fluorouracil nad the clinica
l results in colorectal cancer are reviewed with special emphasis on t
he monthly schedule of low dose leucovorin and 5FU bolus for 5 consecu
tive days (NCCTG-Mayo Clinic regimen) and the bimonthly schedule of hi
gh-dose leucovorin and 5FU bolus plus continous infusion for two conse
cutive days (LV5FU2) which is now considered as a new standard.