1. A method for predicting the therapeutic effect of chemotherapy, which uses an antitumor agent containing α, α, α-trifluorothymidine and 5-chloro-6- (1- (2-iminopyrrolidinyl) methyl) -uracil hydrochloride with a molar ratio of 1: 0.5 to a patient with colorectal cancer, the method comprises the steps of: (1) detecting the presence or absence of a mutation of the KRAS gene in a biological sample obtained from a patient； and (2) predicting that the patient is expected to have a sufficient response to chemotherapy when a KRAS mutation is detected in step (1) .2. The method of claim 1, wherein the mutation of the KRAS gene is a mutation of codon 12 and / or codon 13.3. The method of claim 1 or 2, wherein the patient with colorectal cancer is a patient with colorectal cancer that is persistent or immune to standard therapy. Antitumor agent containing α, α, α-trifluorothymidine and 5-chloro-6- (1- (2-iminopyrrolidinyl) methyl) uracil hydrochloride with a molar ratio of 1: 0.5, for use in the treatment of patients with colorectal cancer , which is believed to have a sufficient response to chemotherapy that uses an antitumor agent containing α, α, α-trifluorothymidine and 5-chloro-6- (1- (2-iminopyrrolidinyl) methyl) uracil hydrochloride in a molar ratio of 1: 0.5, in accordance with the methods of paragraphs. 1-3.5. A method for the treatment of colorectal cancer, including chemotherapy using an antitumor agent containing α, α, α-trifluorothymidine and 5-chloro-6- (1- (2-iminopyrrolidinyl) methyl) uracil hydrochloride with a molar ratio of 1: 0, 5, in a patient with colorectal cancer, which, as1. Способ предсказания терапевтического эффекта химиотерапии, который использует противоопухолевый агент, содержащий α,α,α-трифтортимидин и 5-хлор-6-(1-(2-иминопирролидинил)метил)-урацил гидрохлорид при молярном отношении 1:0,5 на пациента с раком ободочной и прямой кишки,способ включает стадии:(1) детектирования присутствия или отсутствия мутации гена KRAS в биологическом образце,
