Clinical Trial Accrual at Initial Course of Therapy for Cancer and Its Impact on Survival

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  • a Department of Radiation Oncology, Penn State Cancer Institute, and
  • b Department of Public Health Sciences,
  • c Department of Biochemistry and Molecular Biology, and
  • d Department of Surgery, Penn State College of Medicine, Hershey, Pennsylvania.
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Background: This retrospective cohort study sought to characterize the accrual of patients with cancer into clinical trials at the time of diagnosis and analyze the impact of accrual on survival. Methods: The National Cancer Database (NCDB) was queried for patients enrolled in clinical trials at their initial course of treatment for 46 cancers from 2004 through 2015. Descriptive statistics were used to characterize the accrual of patients with cancer in clinical trials at diagnosis, and Kaplan-Meier graphical displays, log-rank tests, odds ratios, and stratified Cox proportional hazards models were used to analyze the impact of accrual on overall survival (OS). Strata were defined using 10 variables. Model-based adjusted survival curves of 2 groups were reverse-generated based on a Weibull distribution. Results: Of 12,097,681 patients in the NCDB, 11,576 (0.1%) were enrolled in trials. Patients in clinical trials typically had metastatic disease (30.9% vs 16.4%; P<.0001), were white (88.0% vs 84.8%; P<.0001), had private/managed care insurance (56.4% vs 41.8%; P<.0001), had fewer comorbidities (Charlson-Deyo score 0: 81.9% vs 75.7%; P<.0001, and Charlson-Deyo scores 1–3: 18.1% vs 24.3%; P<.0001) compared with those not in trials. At a median follow-up of 64 months, enrollment in a clinical trial was associated with improved OS in univariate and stratified analyses, with a median survival of 60.0 versus 52.5 months (hazard ratio, 0.876; 95% CI, 0.845–0.907; P<.0001). Stratified analysis with matched baseline characteristics between patients enrolled and not enrolled in a clinical trial showed superior OS at 5 years (95.0% vs 90.2%; P<.0001). Conclusions: Enrollment in clinical trials at first line of therapy in the United States is exceedingly low and favors young, healthy, white patients with metastatic disease and private insurance who are treated at academic medical centers. Patients with cancer treated in clinical trials live longer than those not treated in trials.

Submitted January 16, 2019; accepted for publication May 16, 2019.

Author contributions: Study concept and design: All authors. Acquisition, analysis, and interpretation of data: All authors. Drafting of the manuscript: Zaorsky. Critical revision: All authors. Statistical analysis: Zhang, Walter, Chinchilli. Administrative, technical, or material support: Zaorsky, Gusani. Study supervision: Zaorsky, Gusani.

Disclosures: Dr. Zaorsky has received grant/research support from Penn State Cancer Institute and is a consultant for Springer Nature, Inc and Weatherby Healthcare. The remaining authors have not received any financial consideration from any person or organization to support the preparation, analysis, results, or discussion of this article.

Correspondence: Nicholas G. Zaorsky, MD, MS, Department of Radiation Oncology, Penn State Cancer Institute, 500 University Drive, Hershey, PA 17033. Email:,

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