Obesity not a big factor in dosing of systemic cancer therapies: ASCO guidelines

Cancer patients should receive full weight-based dosing of chemotherapy regardless of their obesity status, according to an ASCO Guideline Update.

A systematic review of the literature found there was little evidence for capping chemotherapy doses based on concerns about increased toxicity with full weight-based dosing in heavier people.

Additionally, underdosing was more likely to be associated with poorer outcomes.

The update, published in the Journal of Clinical Oncology, said fixed dosing – independent of weight or body surface area (BSA) – should not be used except in the case of bleomycin.

In a separate recommendation, the update noted there was no evidence to support one formula for calculating BSA over another.

The review also found FDA-approved prescribing information for checkpoint inhibitors should be used in all patients, regardless of obesity status.

“Monoclonal antibodies generally have a wider therapeutic window and distribution in blood plasma and extracellular fluid, which correlates less with body size characteristics, making them potentially amenable to fixed dosing,” the update said.

“The paradoxical association between obesity and improved outcomes in patients treated with programmed cell death-1 inhibitors appears to be independent of weight-based dosing of these agents.”

Similarly, the review panel found approved prescribing information for targeted therapies should be used in all patients, regardless of obesity status.

The update also included the recommendation that clinicians respond to treatment-related toxicities in obese patients with cancer in the same ways they do for nonobese patients with cancer.

“Obesity status alone should not play a role in dose modifications in response to toxicity,” it said.

Given most recommendations were based on relatively low quality evidence, the panel said there were clear implications for future research.

“Body composition analysis should be a consideration in the assessment of patients beginning cancer treatment, particularly in the context of clinical trials evaluating novel anticancer therapies. Prospective studies should explore the role of body composition in predicting dose-limiting toxicities and the relationship between dose modification and clinical outcome.”


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