The invention surprisingly found that antcin or an ester derivative, salt or a composition thereof in combination with an anti-tumor drug provides unexpected efficacy in inhibiting tumor, while retaining normal cells at high viability. In addition, the amount of the anti-tumor drug in chemotherapy can be reduced by combinatorially using antcin or an ester derivative, salt or a composition thereof in view of the fact that they play a role in adjuvant therapy.本發明驚訝地發現,樟芝酸或其酯、衍生物、鹽或組合物與抗腫瘤藥物組合在抑制腫瘤方面提供出乎意料的功效,同時使正常細胞維持高生存力。另外,鑒於樟芝酸或其酯衍生物、鹽或組合物在輔助治療中起一定作用的事實,所述抗腫瘤藥物在化學治療中的量可透過組合使用樟芝酸或其酯衍生物、鹽或組合物而減少。