News Details
New Research in JNCCN Raises Concerns about Clinical Trial Bias from Undisclosed Censoring
Cancer researchers call for more transparency on who drops out of clinical trials and why.
PLYMOUTH MEETING, PA [December 15, 2021] — New research in the December 2021 issue of JNCCN—Journal of the National Comprehensive Cancer Network found that only 59% of oncology clinical trials studied provided adequately-defined rules for censoring. The researchers examined published randomized control trials supporting FDA approval for treatments for solid tumors from January 2015 through December 2019—and found that for 33 out of 81 studies, it was not clear in the publication why or how patients were being censored.
Censoring is defined in this context as the practice of removing patients from follow-up before experiencing the outcome of interest; for instance, if the main outcome of a cancer treatment trial is survival and the patient experiences a heart attack and withdraws from the trial, they may no longer be followed-up. If the proportion of patients who are censored is not evenly balanced between comparison groups, this can introduce bias and makes it difficult to interpret the results of trials.
“We hope that our findings will prompt investigators and journals to report early drug discontinuation, withdrawal of consent, loss to follow-up, and censoring more transparently in trial publications. This would allow patients and clinicians to make more informed decisions regarding the potential benefits of a treatment,” said lead researcher Brooke E. Wilson, MBBS, MSc, University of Toronto. “Regulatory authorities and journals can play a leadership role in mandating improved transparency and ensuring that censoring data be made publicly available.”
The authors compiled a list of goals and recommendations to improve transparency and reporting in clinical trials. Those goals include:
- Minimize the chance of post-randomization bias
- Improve transparency regarding censoring methods in oncology trials
- Explore the impact of censoring on trial results
- Improve the handling of transparency of missing outcome data in trial results
- Acknowledge the potential impact of censoring on the interpretation of results
- Provide transparent information regarding early drug discontinuation and withdrawal of consent or loss to follow-up
“In trials with survival outcomes, it’s important to clearly and carefully define censoring,” commented Elizabeth A. Handorf, PhD, Associate Research Professor, Fox Chase Cancer Center, who was not involved in this research. “It’s possible that different ways of defining or handling censoring could change the results. It’s concerning that so few studies presented sensitivity analyses, as this is the best way for the reader to understand the potential impact of the study’s definitions and assumptions. I was surprised to see that 54 studies had a planned sensitivity analysis for censoring rules but only 3 published the results. Even if a sensitivity analysis shows no difference, those results are useful to include.”
To read the entire study, visit JNCCN.org. Complimentary access to “Quantifying Withdrawal of Consent, Loss to Follow-Up, Early Drug Discontinuation, and Censoring in Oncology Trials” is available until March 10, 2022.
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About JNCCN—Journal of the National Comprehensive Cancer Network
More than 25,000 oncologists and other cancer care professionals across the United States read JNCCN—Journal of the National Comprehensive Cancer Network. This peer-reviewed, indexed medical journal provides the latest information about innovation in translational medicine, and scientific studies related to oncology health services research, including quality care and value, bioethics, comparative and cost effectiveness, public policy, and interventional research on supportive care and survivorship. JNCCN features updates on the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®), review articles elaborating on guidelines recommendations, health services research, and case reports highlighting molecular insights in patient care. JNCCN is published by Harborside. Visit JNCCN.org. To inquire if you are eligible for a FREE subscription to JNCCN, visit NCCN.org/jnccn/subscribe. Follow JNCCN on Twitter @JNCCN.
About the National Comprehensive Cancer Network
The National Comprehensive Cancer Network® (NCCN®) is a not-for-profit alliance of leading cancer centers devoted to patient care, research, and education. NCCN is dedicated to improving and facilitating quality, effective, equitable, and accessible cancer care so all patients can live better lives. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) provide transparent, evidence-based, expert consensus recommendations for cancer treatment, prevention, and supportive services; they are the recognized standard for clinical direction and policy in cancer management and the most thorough and frequently-updated clinical practice guidelines available in any area of medicine. The NCCN Guidelines for Patients® provide expert cancer treatment information to inform and empower patients and caregivers, through support from the NCCN Foundation®. NCCN also advances continuing education, global initiatives, policy, and research collaboration and publication in oncology. Visit NCCN.org for more information and follow NCCN on Facebook @NCCNorg, Instagram @NCCNorg, and Twitter @NCCN.