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.