The interactions among drugs,tumor and host are critical for a response to therapy and for outcome.Anticancer herbs used in Chinese medicine are classified into 4 groups based on their target (tumor,patient and drug) as follows:eliminating pathogenic factors,strengthening the body resistance,enhancing effects of chemotherapy and detoxication of chemotherapy. Correspondingly,anticancer drugs used in Western medicine can be classified into 4 groups as follows:cytotoxic drugs,biological response modifiers,chemosensitizers and chemoprotectants. Based on the theory of Chinese medicinal formulas,prescriptions are composed of four constituents,namely,primary constituent (main component of the formula prescription),minister constituent (second component of formula prescription),adjuvant constituent (adjuvant component of the formula prescription) and messenger constituent (component making the formula prescription targeting pathological tissues).To control the interaction among drugs and to modulate the interaction among the tumor,patient and drugs,we suggest that combined therapy for Western medicine might include 4 constituents,i.e.,primary,cooperative,adjuvant and modulatory constituent. Cytotoxic drugs frequently are used as primary and cooperative constituents,whereas biological response modifiers and biochemical modulators are usually regarded respectively as adjuvant drugs and modulatory constituents. We believe these new concepts may be helpful for the aim of appropriately designing,evaluating or providing combination therapy. The interactions among drugs, tumor and host are critical for a response to therapy and for outcome. Anticancer herbs used in Chinese medicine are classified into 4 groups based on their target (tumor, patient and drug) as follows: eliminating pathogenic factors, strengthening the body resistance, enhancing effects of chemotherapy and detoxication of chemotherapy. Correspondingly, anticancer drugs used in Western medicine can be classified into 4 groups as follows: cytotoxic drugs, biological response modifiers, chemosensitizers and chemoprotectants. Based on the theory of Chinese medicinal formulas, prescriptions are composed of four constituents, namely, primary constituent (main component of the formula prescription), minister constituent (second component of formula prescription), adjuvant constituent (adjuvant component of the formula prescription) and messenger constituent (component making the formula prescription targeting pathological tissues) .To control the interaction among drugs and to mo dulate the interaction among the tumor, patient and drugs, we suggest that combined therapy for Western medicine might include 4 constituents, ie, primary, cooperative, adjuvant and modulatory constituent. Cytotoxic drugs frequently used as primary and cooperative constituents, among biological response modifiers and biochemical modulators are finally as as as adjuvant drugs and modulatory constituents. We believe these new concepts may be helpful for the aim of of designing, evaluating or providing combination therapy.