Obesity and dose individualization in cancer chemotherapy: The role of body surface area and body mass index

It is generally accepted that anti-neoplastic chemotherapy dose should be calculated according to body surface area (BSA). This approach does not account for the presence of obesity. Hence, patients with the same BSA will receive the same chemotherapy dose, regardless the presence of obesity. Since this may cause of toxicity in some obese patients, practice of limit BSA is usual. Currently, the body mass index (BMI) is largely used as a marker of obesity and both BSA and BMI include only height (h) and weight(w) in their formula. We put forward the hypothesis that the BMI should also be taken in account for calculation of chemotherapy dose for obese patients (BMI > 30 kg/m2). In this article, we present a correction to BSA (CBSA) based on the BMI to be tested in obese patients. Our main result is given by the equationCBSA=K[α1h(α2+2κ)w(α3-κ)],whereK=1100(2κ)and κ, α1, α2, α3 are constants. We show examples of how to calculate the CBSA. This simple strategy may limit drug exposition and maintain greater efficacy than a fixed limitation of BSA.