Committee Connection

ASCO Recommends Appropriate Weight-based Dosing of Cytotoxic Chemotherapy for Obese Patients

29 Jun 2012 6:32 PM

July 2012: In order to assist oncologists in providing optimal curative care to patients who are overweight or obese, ASCO recently released a clinical practice guideline on “Appropriate Chemotherapy Dosing for Obese Adult Patients With Cancer,” which covers both intravenous and oral chemotherapy.

“This guideline will reduce the uncertainty and variation of chemotherapy dosing in clinical practice and result in more consistent evidence-based treatment and improved clinical outcomes,” said Gary H. Lyman, MD, MPH, FASCO, FRCP, of Duke University School of Medicine and Co-Chair of the Expert Panel that developed the recommendations.

The guideline highlights the fact that many overweight and obese patients receive limited or reduced chemotherapy doses and discusses the evidence for using actual body weight to determine the appropriate cytotoxic chemotherapy dosing essential for cure. More than 60% of U.S. adults have a body mass index (BMI) over 25% and are considered overweight or obese.

Safety and importance
Based on the Expert Panel’s literature review, practice pattern studies demonstrate that up to 40% of obese patients receive limited chemotherapy doses that are not based on actual body weight. Concerns about toxicity or overdosing in obese patients with cancer, based on the use of actual body weight, are unfounded. Studies confirm the safety and importance of full weight-based dosing. For example, even when chemotherapy doses are calculated according to actual body weight, obese patients are less likely to have bone marrow suppression.

“Many oncologists are not aware that full weight-based doses are used in patients on clinical trials. Disseminating the evidence against dose limits is one way to overcome the underdosing we have seen in up to 40% of patients. This is particularly important given the prevalence of obesity and the relationship between obesity and cancer incidence and outcome,” said Jennifer J. Griggs, MD, MPH, of the University of Michigan and an Expert Panel Co-Chair.

According to the guideline, clinicians should order and deliver chemotherapy doses based on a patient’s actual body weight. Toxicity is no greater for obese patients with appropriate dosing although comorbidities must always be considered. If dose is reduced as a result of toxicity, the clinician should consider returning to the appropriate weight-based dose when the toxicity is resolved and monitoring the patient’s reaction carefully. There are potential serious harms in underdosing patients who are obese in that efficacy may be compromised. The potential benefits of weight-based dosing include maximizing the potential benefit of chemotherapy.

Exceptions to this general recommendation, where fixed doses are acceptable, are noted within the full guideline.

Clinical resources, tools, and further reading are available, including: This new guideline topic for ASCO was published online by the Journal of Clinical Oncology in April 2012, and in print, May 1, 2012; a summary was published in the Journal of Oncology Practice.

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