Therefore, a patient’s adjusted ideal body weight or ideal body weight is sometimes substituted to calculate the dose. Many chemotherapeutic agents do not include overweight- or obese-specific dosing recommendations in their prescribing information, which may persuade practitioners to use the “traditional” and consequently lower doses that they are familiar with.
As a direct result of this dosing unfamiliarity, the American Society of Clinical Oncology (ASCO) developed a set of clinical practice guidelines in 2012 that address the dosing of chemotherapy in overweight and obese patients with cancer.4
ASCO recommended the use of actual body weight in overweight and obese patients, especially since they did not find any data to support increased risk of short- or long-term toxicity secondary to higher doses.
In addition, the under-dosing of overweight and obese patients may be a significant contributor to the overall increased risk of mortality seen in these patients.
The ASCO guidelines also recommended the utilization of standard dose-reduction protocols in obese patients who experience high-grade toxicity as there was no significant data to support the need for more substantial dose reductions when compared to non-obese patients.
The guidelines called for future studies aimed at investigating the pharmacodynamics and pharmacokinetic properties of chemotherapeutic agents in overweight and obese patients to further elucidate dosing strategies.4
Many of the clinical studies used to determine the affect of obesity on the dosing of chemotherapy, such as those analyzed while developing the ASCO guidelines, are retrospective or observational and not prospective, randomized controlled trials.
Therefore the ASCO guidelines should be utilized as one of many factors considered when determining the dosing of a patient’s chemotherapy.
Each patient requires an individualized approach, during which the patient’s comorbidities and overall health and wishes must be taken into account.
- Ligibel JA, Alfano CM, Courneya KS, et al. American Society of Clinical Oncology position statement on obesity and cancer. J Clin Oncol. 2014;32(31):3568-3574.
- Renehan AG, Tyson M, Egger M, et al. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. Lancet. 2008;371(9612):569-578.
- Bhaskaran K, Douglas I, Forbes H,et al. Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5·24 million UK adults. Lancet. 2014;384(9945):755-765.
- Griggs JJ, Mangu PB, Anderson H, et al. Appropriate chemotherapy dosing for obese adult patients with cancer: American Society of Clinical Oncology clinical practice guideline. J Clin Oncol. 2012;30(13):1335-1561.