How are cytostatics dosed?

Author:  Gesche Tallen, MD, PhD, Editor:  Maria Yiallouros, Reviewer:  Prof. Dr. med. Dr. h.c. Günter Henze, English Translation:  Hannah McRae, Last modification: 2015/04/27

For an optimal and successful cancer treatment, chemotherapy should be capable of eliminating the cancer cells, while leaving the healthy cells undamaged. Therefore, the cytostatic agent must be given in a feasible dosage, at the right time, and it must be administered appropriately to successfully exert its effects.

In general, higher dosages of chemotherapy are not always providing more anticancer effects, because their efficacy also depends on the number of malignant cells that are dividing or are about to divide when treatment is given.

Cells in non-dividing, resting cell cycle phases are hard to damage by chemotherapy. For this reason, certain cytostatics are given in lower doses and over a longer period of time. This strategy helps not to miss the moment when a resting cancer cell starts dividing again, and also, to keep the risk of side-effects as low as possible. In some situations, however, giving high doses of chemotherapy in short periods of time is more effective, since it may prevent a cancer cell from repairing the damage and subsequently developing resistance to treatment.

Taken together, different types of cancer require different cytostatic agents given in different dosages and at different times of treatment. Both dosage and timing of chemotherapy are adjusted to the patient's individual situation.

Usually, a team of pharmacists and oncologists calculates the dosages of the different cytostatic drugs to be given based on the recommendations of the current treatment protocol as well as the patient’s body surface/weight/size.

Prior to the administration of any cytostatic drug, its calculated dosage will be checked by other members of the treatment team for safety reasons. If any side effects occur – and if so, depending on their frequency and degree – the dose of the responsible agent is usually reduced and adjusted to the patient's individual situation.