New research has found that some breast cancer trials are failing to provide appropriate control group treatments, affecting the outcomes of these studies.

Researchers from the University of Sydney have found that 29 percent of breast cancer clinical trials reviewed failed to provide control group treatment in line with the current standard of care.

The researchers analysed 210 breast cancer trials - the most frequently studied cancer type worldwide - that included more than 229,000 patients, and found that the treatment supplied to women in the control arms of the study was inappropriate in nearly a third of trials.

The study was published in the Journal of the National Comprehensive Cancer Network (US).

Lead researcher Dr Rachel Dear, Medical Oncologist and Senior Lecturer at Sydney Medical School, said it is imperative that clinical trials are carefully designed to ensure they are scientifically and ethically sound.

“These inconsistencies affect the reliability and accuracy of clinical trial results and can also impact patient care in the long term.

“Some of the most common inconsistencies were type of medications prescribed, dosage and type of treatment.

“We saw an inconsistency in the choice of controls used in the trials which undermined 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.

“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 said.

The researchers recommended that further investigation into determining the optimal standard of care for clinical trial control groups be completed.

“We were somewhat surprised to find few guidelines 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 of groups of clinical trials,” said Dr Dear.

The study was led by Dr Rachel Dear, Sydney Medical School, with researchers Alexandra Barratt and Kevin McGeechan from the School of Public Health, and Dr Meg Barnet and Professor Martin Tattersall from Sydney Medical School.