ASCO: Stop Underdosing Obese Cancer Patients - OncologySTAT

ASCO: Stop Underdosing Obese Cancer Patients - OncologySTAT



Excerpt:





"Chemotherapy doses should be tailored for obese cancer patients based on their actual body weight, not their ideal body weight, according to a new practice guideline from the American Society of Clinical Oncology.



There is no evidence that full-weight-based chemotherapy doses cause greater toxicity than adjusted doses, and concerns about "overdosing" obese cancer patients are unfounded, a panel of experts wrote in a report published online April 2 in the Journal of Clinical Oncology.



A systematic review of the literature showed that many overweight and obese cancer patients continue to receive underdoses of intravenous and oral cytotoxic drugs because of "considerable uncertainty among physicians about optimal dose selection," even though research has confirmed that full-weight-based dosing is both safe and crucial to the patients' survival.



"Many oncologists continue to use either ideal body weight or adjusted ideal body weight, or to cap the body surface area at, for example, 2.0 m², rather than use actual body weight to calculate body surface area," said Dr. Jennifer J. Griggs of the University of Michigan, Ann Arbor, and her associates on the expert panel for ASCO's new practice guideline.



As a result, chemotherapy dosing varies widely in overweight and obese patients, with as many as 40% receiving less than optimal dosing. This "may explain, in part, the significantly higher cancer mortality observed in overweight and obese individuals," they noted."

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Most of the studies concerned breast, ovarian, colon, and lung cancers, the authors said. As little data in the literature addressed dosing for novel agents such as tyrosine kinase inhibitors, immunotherapies such as interleukin-2 or interferon, or monoclonal antibodies, the guideline did not address these agents.



A summary of the guideline (J. Clin. Oncol. 2012 [doi:10.1200/JCO.2011.39.9436]) lists these key recommendations:



• Actual body weight should be used to select cytotoxic chemotherapy doses, regardless of obesity status. There is no evidence that either short- or long-term toxicity is increased with this approach.

• Use the same strategy in obese patients as in other patients for dose reductions, taking into account the type and severity of toxicity, any comorbid conditions, and whether the aim of treatment is cure or palliation. There is no evidence that greater dose reductions are needed for obese patients. Also, consider resuming the full-weight-based dose for subsequent chemotherapy cycles, especially if a possible cause of toxicity (such as impaired renal or liver function) has resolved.

• Consider fixed dosing only with select cytotoxic agents for which maximal dosing limits have been established, such as vincristine, carboplatin, or bleomycin.

• Calculate body surface area using any of the standard formulas currently available. There is no evidence to support using one formula over any other.

• Further research is needed into the pharmacokinetics and pharmacogenetics of chemotherapy dosing for obese patients, who have been excluded from many anticancer drug trials."



{Reference link and to read full article: OncoSTAT}

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