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29% of breast cancer trials do not establish control arm, study says

Published on 28/09/17 at 09:18am

As part of the effort to conduct ethical and scientifically safe, effective clinical trials, the standard for researchers carrying out such studies is to use randomised control arms in order to assess a therapy in comparison to existing standard of care. However, even though this is considered an essential norm, researchers from the University of Sydney have found that as much as 29% of trials in breast cancer did not adequately establish a control arm.

This standard is set out in the Declaration of Helsinki, a set of guidelines to be used in human clinical trials, which states: “benefits, risks, burdens, and effectiveness of a new method should be tested against those of the best current prophylactic, diagnostic, and therapeutic methods.”

The team made the discovery by analysing Phase 3 randomised clinical trials in breast cancer worldwide between 2004 and 2014, which totalled 210 trials and more than 229,000 patients. Comparing the control arm drugs and dosing to the concurrent recommendations within the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for US studies, and the German Gynecological Group (AGO) for European studies, it was found that 60 trials failed to provide control group treatment in line with the concurrent standard of care – 11 of 83 in the US and 49 of 127 in Europe. The proportion of inadequate control arms was much higher in Europe, at 39% compared to 11% in the US.

"Inconsistency of choice of control arm undermines the quality of evidence generated by clinical trials, which in turn impacts systemic reviews, the development of clinical practice guidelines, planning of future trials, and, ultimately, patient care and outcomes," explained lead author Dr Rachel F Dear. "An inappropriate comparator, such as a drug or dose that is less effective than the standard of care, may result in a new treatment appearing more effective than it really is. Another type of inappropriate comparator may be a treatment that may not be inferior but is not provided or accepted as the standard of care, which will result in outcomes that are difficult to interpret and implement in the context of multiple standards across multiple trials."

She continued: "We were somewhat surprised to find little guidance available internationally to help trial investigators decide what care is appropriate to give women who are randomised to the comparison or "standard care" arm of clinical trials. Better guidance needs to be available to investigators to ensure provision of the best current care to patients in control groups of clinical trials."

Meena Moran, Director of the Yale Radiation Breast Program at Yale Cancer Center/Smilow Cancer Hospital, commented on the findings: "This study highlights the complexity when defining 'standard care' for the control arm of phase III clinical trials. Other factors that need to be considered include how new fluxes of information make capturing standard of care in real time difficult, and controversies surrounding trials conducted outside of the United States. Nevertheless, this body of work provides a great starting point for identifying any deviations from 'standard care' in clinical trials that with further investigation, may prove to be clinically relevant or detrimental for patients."

Matt Fellows

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