Cancer chemotherapy.

The Authors describe and discuss the biological bases and fundamental clinical principles for proper and rational anti-tumor chemotherapy. The effectiveness of chemotherapy depends essentially on the following factors: 1) kinetic phase of the neoplastic cells, 2) penetration of the drugs within the tumor mass, 3) segregation of tumor cells in pharmacological sanctuaries, 4) presence of drug-resistant cell phenotypes. It follows that proper chemotherapy must: 1) begin early, when the tumor is small and the number of drug-resistant cells and cells in G0 is small, 2) involve the simultaneous use of several drugs acting on cells in different phases of replication without overlapping toxicity and cross-resistance, 3) be utilized at high drug dosages and at optimum time intervals between one cycle and another so that the greatest number of neoplastic cells can be destroyed as soon as possible in order to prevent regrowth of the tumor and development of drug-resistant cell strains.