Optimal timing of adjuvant chemotherapy in mouse models

In three mouse tumor models the effect of timing of adjuvant chemotherapy with a single dose of cyclophosphamide was studied. In one tumor, preoperative adjuvant therapy was better than postoperative therapy. In a second tumor, the reverse was the case, and in the third model there was no difference resulting from variation in the timing of cytostatic drug therapy. Obviously, the concept that a standard drug dose always gives a constant relative cell kill is not always a valid simplification of dose-effect relationships in chemotherapy.