Drug Combinations It used to be that anticancer drugs were given one at a time. But now combinations of drugs are usually given, all according to a plan designed to inhibit or kill as many cancer cells as possible.
Drugs that attack tumor cells at every stage of their life cycle—called non-cell-cycle-specific drugs—may be given first to reduce the size of the tumor. This may activate the remaining cells to divide. When they do, cell-cycle-specific drugs that attack dividing cells will be given. Other sequences of other drugs can also be devised to maximize the therapeutic effect.
This is much like fighting a war, making sure you use all your forces on several fronts with repeated attacks. Your chances of winning the battle are greatly improved.
Drug Resistance There's another good reason for giving drug combinations: it reduces the chance that you'll develop a resistance to any one drug.
Resistance is one very common reason why these agents fail to do what they're supposed to. A course of chemotherapy is often quite successful at first. The cancer responds, leading to a remission . But then, even though the drugs are still being given, there is a relapse and the cancer starts to grow again. A resistance to therapy has developed just like the resistance to penicillin or other antibiotics that can develop when treating an infection.
