Provided are: a method for predicting the therapeutic effect of a chemotherapy in a breast cancer patient and an anti-tumor agent for treating a cancer patient on whom it has been predicted that the chemotherapy is highly likely to have a satisfactory therapeutic effect. Specifically provided are: a method for predicting the therapeutic effect of a chemotherapy in a breast cancer patient, which utilizes the expressed amount of a CRP as a measure and an anti-tumor agent for treating a cancer patient on whom it has been predicted that the anti-tumor agent is highly likely to have a therapeutic effect by the above-mentioned predicting method.本發明提供一種針對乳癌患者之化學療法之治療效果之預測方法、及預測到該化學療法顯示充分之治療效果之可能性較高的癌患者之治療用抗腫瘤劑。其係以CRP之表現量為基準的針對乳癌患者之化學療法之治療效果之預測方法、及藉由該預測方法而預測到顯示治療效果之可能性較高的癌患者之治療用抗腫瘤劑。
