This invention provides compositions and methods for preventing or treating a malignant tumor in a mammal in need thereof, by administering to the mammal a therapeutically effective amount of a composition comprising RNAi molecules, which RNAi molecules can be active in reducing expression of Hsp47, or a combination of RNAi molecules active for Hsp47 and p21.本發明提供用於預防或治療有此需要之哺乳動物的惡性腫瘤之組成物及方法,該方法係藉由投予該哺乳動物治療有效量之組成物,該組成物包含具有能減少Hsp47表現之活性的RNAi分子或具有能減少Hsp47和p21表現之活性的RNAi分子之組合。