Summary:Individual chemotherapy dosing by either body weight or body surface area has become the standard practice in oncology. As pharmacokinetics of many cytostatic drugs only partially depend on the size of the body, big differences in exposure to cytostatics occur among individual patients when body-size-based dosing is used. Currently, no guidelines exist for chemotherapy dosing calculations in obese patients. Despite of the fact that many pharmacokinetic studies show higher exposure to some cytostatics in obese patients when dosed by their actual weight, clinical studies have not confirmed greater toxicity. With the lack of studies evaluating clinical outcome in the relationship to chemotherapy dosing in obese patients it is possible to choose a dose based on actual weight, favoring increased dose intensity, when treating a patient with curable malignancy. The possible method for dose reduction in massively obese patients may be to use the mean of actual and ideal body weight. In other cases lower doses may be preferable at the beginning with agradual escalation of 10-20% per cycle up to the maximum tolerable level. In a high-dose chemotherapy with stem cell transplantation (doses close to lethal toxicity) most centers use dosing between ideal and actual body weight of obese patients but clinical practice among centers differ significantly.
Discretion on cytostatic dosage in obese patients
