Analysis of Female Participant Representation in Registered Oncology Clinical Trials in the United States from 2008 to 2020

Nirosha D Perera; Tiffany R Bellomo; Walker M Schmidt; Henry K Litt; Margaret Shyu; MaKenna A Stavins; Max M Wang; Alexander Bell; Massoud Saleki; Katherine I Wolf; Ruxandra Ionescu; Jacqueline J Tao; Sunjong Ji; Ryan M O'Keefe; Matthew Pun; Jordan M Takasugi; Jecca R Steinberg; Ronald S Go; Brandon E Turner; Amit Mahipal

doi:10.1093/oncolo/oyad009

Analysis of Female Participant Representation in Registered Oncology Clinical Trials in the United States from 2008 to 2020

Oncologist. 2023 Jun 2;28(6):510-519. doi: 10.1093/oncolo/oyad009.

Authors

Nirosha D Perera¹, Tiffany R Bellomo², Walker M Schmidt³, Henry K Litt⁴, Margaret Shyu⁵, MaKenna A Stavins⁶, Max M Wang⁷, Alexander Bell⁸, Massoud Saleki⁹, Katherine I Wolf¹⁰, Ruxandra Ionescu⁶, Jacqueline J Tao¹¹, Sunjong Ji¹⁰, Ryan M O'Keefe¹², Matthew Pun¹⁰, Jordan M Takasugi⁶, Jecca R Steinberg¹³, Ronald S Go¹⁴, Brandon E Turner¹⁵, Amit Mahipal^{14

16}

Affiliations

¹ Department of Medicine, Mayo Clinic, Rochester, MN, USA.
² Department of Vascular Surgery, Massachusetts General Hospital Harvard Medical Center, Boston, MA, USA.
³ Alix School of Medicine, Mayo Clinic, Rochester, MN, USA.
⁴ Department of Medicine, University of California San Francisco, San Francisco, CA, USA.
⁵ Department of Medicine, Mount Sinai, New York, NY, USA.
⁶ School of Medicine, University of Washington, Seattle, WA, USA.
⁷ Feinberg School of Medicine, Northwestern, Chicago, IL, USA.
⁸ School of Medicine, University of California San Francisco, San Francisco, CA, USA.
⁹ Department of Medicine, University of Vermont, Burlington, VT, USA.
¹⁰ Department of Medicine, University of Michigan Medical Center, Ann Arbor, MI, USA.
¹¹ Department of Medicine, New York-Presbyterian Weill Cornell, New York, NY, USA.
¹² Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
¹³ Department of Obstetrics & Gynecology, Northwestern, Chicago, IL, USA.
¹⁴ Department of Oncology, Mayo Clinic, Rochester, MN, USA.
¹⁵ Department of Radiation Oncology, Dana Farber Cancer Institute Harvard Medical Center, Boston, MA, USA.
¹⁶ Department of Oncology, University Hospitals, Case Western University, Cleveland, OH, USA.

Abstract

Background: Female underrepresentation in oncology clinical trials can result in outcome disparities. We evaluated female participant representation in US oncology trials by intervention type, cancer site, and funding.

Materials and methods: Data were extracted from the publicly available Aggregate Analysis of ClinicalTrials.gov database. Initially, 270,172 studies were identified. Following the exclusion of trials using Medical Subject Heading terms, manual review, those with incomplete status, non-US location, sex-specific organ cancers, or lacking participant sex data, 1650 trials consisting of 240,776 participants remained. The primary outcome was participation to prevalence ratio (PPR): percent females among trial participants divided by percent females in the disease population per US Surveillance, Epidemiology, and End Results Program data. PPRs of 0.8-1.2 reflect proportional female representation.

Results: Females represented 46.9% of participants (95% CI, 45.4-48.4); mean PPR for all trials was 0.912. Females were underrepresented in surgical (PPR 0.74) and other invasive (PPR 0.69) oncology trials. Among cancer sites, females were underrepresented in bladder (odds ratio [OR] 0.48, 95% CI 0.26-0.91, P = .02), head/neck (OR 0.44, 95% CI 0.29-0.68, P < .01), stomach (OR 0.40, 95% CI 0.23-0.70, P < .01), and esophageal (OR 0.40 95% CI 0.22-0.74, P < .01) trials. Hematologic (OR 1.78, 95% CI 1.09-1.82, P < .01) and pancreatic (OR 2.18, 95% CI 1.46-3.26, P < .01) trials had higher odds of proportional female representation. Industry-funded trials had greater odds of proportional female representation (OR 1.41, 95% CI 1.09-1.82, P = .01) than US government and academic-funded trials.

Conclusions: Stakeholders should look to hematologic, pancreatic, and industry-funded cancer trials as exemplars of female participant representation and consider female representation when interpreting trial results.

Keywords: female participant representation; oncology clinical trials; participation to prevalence ratio.

MeSH terms

Databases, Factual
Female
Humans
Male
Medical Oncology
Neoplasms* / epidemiology
Neoplasms* / therapy
Odds Ratio
Prevalence
United States / epidemiology

Grants and funding

T32 GM007863/GM/NIGMS NIH HHS/United States