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October 11, 2022
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Patients with obesity ‘well-represented’ in cancer clinical trials

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Patients with cancer and obesity appeared well-represented in clinical trials, indicating that clinical trial findings may be generalizable to this patient population, according to study results published in JAMA Network Open.

Background and methods

Previous research has shown that cancer clinical trial reports do not include adequate information about enrollment of patients with obesity, Riha Vaidya, PhD, researcher at SWOG Statistical and Data Management Center at Fred Hutchinson Cancer Center, told Healio.

Obesity prevalence between 2015 and 2016
Data derived from Vaidya R, et al. JAMA Netw Open. 2022;doi:10.1001/jamanetworkopen.2022.34445.
Riha Viadya
Riha Vaidya

“Examining this enrollment information is important to ensure that trial findings are applicable to this population of patients,” Vaidya said. “It becomes even more pertinent with rising obesity rates and the research linking obesity to worse cancer outcomes and to treatment toxicities. We therefore decided to examine obesity prevalence among patients enrolled on clinical trials conducted by the SWOG Cancer Research Network, as SWOG has collected the necessary data at trial enrollment for some time now, which allowed us to conduct a comprehensive examination.”

Vaidya and colleagues examined the prevalence of obesity and combined overweight and obesity between 1986 and 2016 among 23,926 patients with cancer (median age, 58 years; 73.5% women; 83.1% white) included in SWOG Cancer Research Network clinical trials for obesity-related cancers and compare trends with corresponding U.S. trends.

Researchers used multivariable logistic regression analysis adjusted for demographic and clinical factors to analyze patient height and weight gathered at clinical trial enrollment.

Findings

Results showed unadjusted obesity rates increased from 23.5% between 1986 and 1990 to 42.3% between 2011 and 2016.

Researchers additionally identified an increased linear trend in obesity (OR per 5-year increase = 1.23; 95% CI, 1.21-1.26) that persisted even after adjusting for demographic and clinical characteristics and appeared consistent for combined overweight and obesity (OR per 5-year increase = 1.22; 95% CI, 1.2-1.25).

Of note, the odds of overweight/obesity throughout time differed according to cancer type, study stage and treatment type (all P for interaction < .001), but not by sex or race and ethnicity.

Moreover, researchers found the overall increasing trend in obesity prevalence between 1999 and 2000 to between 2015 and 2016 appeared higher among patients included in clinical trials (21.3% to 49.1%) compared with the overall U.S.-adult population (30.5% to 39.6%; P for trend = .03), but similar to that of U.S. cancer survivors (18.9% to 42.2%).

Implications

“Our findings imply that patients with obesity are well-represented in clinical trials, and this improves confidence in the generalizability of trial findings,” Vaidya said. “This is critical considering that trial findings play an important role in the development of clinical practice guidelines.”

The trends observed among trial participants are also indicative of the rising burden of obesity among patients with obesity-related cancers, she added.

“This work ties into a larger body of research examining diversity and representativeness of trial participants, which we will continue to work on,” Vaidya said. “Answering these questions about patient representation could help identify potential barriers to clinical trial participation.”

For more information:

Riha Vaidya, PhD, can be reached at rrvaidya@fredhutch.org.