Action

There are three broad groups of chemotherapeutic drugs, depending on the toxicity and the phase of the cell cycle:

• toxicity independent of phases of cell cycle, including Go
• specific to the cell cycle, but not active in Go
• phase specific drugs, e.g. only in S phase

Principles:

• a constant fraction of tumour cells are killed by a given dose of a given drug
• there is a dose-response relationship