The present invention relates to a method for treating a cancer comprising orally administering a composition containing α,α,α-trifluorothymidine (FTD) and 5-chloro-6-(1-(2-iminopyrrolidinyl)methyl)uracil hydrochloride in a molar ratio of 1:0.5 at a dose of 20 to 80 mg/m2/day in terms of FTD in 2 to 4 divided portions per to patients in need of the treatment.