Cancer Trials versus the Real World in the United States
Waddah B Al-Refaie, MD*, Selwyn M Vickers, MD, Wei Zhong, MD*, David Rothenberger, MD, Elizabeth B Habermann, MD*
University of Minnesota, Minneapolis, MN
Objectives: Federal policies have been instituted to mitigate under-enrollment to cancer trials in the US. We hypothesized that enrollment patterns to cancer trials have improved in a contemporary era.
Methods: The 2001 - 2008 California Cancer Registry was used to determine patterns and predictors of enrollment in clinical trials for stage 0-IV solid organ malignant tumors. Multivariate techniques were used to identify predictors of enrollment to cancer protocols controlling for covariates.
Results: Only 1,566 (0.64%) out of 244,528 patients were enrolled in cancer trials. Black patients were less likely than whites to enroll in trials (0.48% vs. 0.67%, p<0.05). On multivariate analysis, older persons (> 65 years), early stage cancer, and those with lung or gastrointestinal cancers were less likely to be enrolled into cancer trials. For non-breast cancer protocols, these estimates showed similar results. Though approaching significance, black, underinsured, and uninsured patients showed trends toward under-enrollment (Table).
Conclusion: In addition to profoundly low accrual rates to cancer protocols overall, vast underrepresentation by age, cancer stage and site continue to exist. The generalizability of these trials to a real world perspective remains an open question. Physicians, payers, the NCI, and other stakeholders need to develop broader cancer trials to benefit the millions of patients with cancer in the U.S.
Table. Multivariate analysis of predictors of enrollment to cancer protocols*
|Factors||All cancer sites|
OR (95% CI)
|Breast cancer excluded|
OR (95% CI)
|N (enrolled in trials)||1,566||549|
|Age > 65 vs. < 65 yrs||0.42 (0.36-0.50)||0.43 (0.34-0.55)|
|Black vs. white race||0.78 (0.60-1.01)||0.64 (0.35-1.17)|
Medicaid vs. private
Uninsured vs. private
|Early vs. advanced cancer stage||0.61 (0.53-0.70)||0.50 (0.41-0.62)|
|Solid cancer site|
Lung vs. breast
GI vs. breast
Melanoma vs. breast
|* adjusting for gender and year of diagnosis. Abbreviation: OR, odds ratio; CI, confidence intervals.|
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