Clinical trials of cancer therapies tend to be smaller and less rigorous than those conducted in other disease areas, raising questions about oncology treatments’ effectiveness in practice, a new analysis has found.

A team of researchers led by Dr Bradford Hirsch, assistant professor of medicine at Duke University School of Medicine in the US, looked at nearly 9000 oncology clinical research studies registered on the website between 2007 and 2010.

The analysis was conducted as part of the Clinical Trials Transformation Initiative, a public-private partnership set up by the US Food and Drug Administration (FDA) and Duke University to identify practices that can improve the quality and efficiency of clinical trials. Findings were published online in the journal JAMA Internal Medicine.

Small, early-phase

Hirsch and his colleagues found that the oncology studies were predominantly small, early-phase trials evaluating a single treatment without comparing it with other therapies or randomising patients to different treatments, they reported.

This orientation toward less robust trial designs is in significant contrast to other fields of medicine, the Duke researchers noted.

It is partly down to the accelerated-approval process embraced by the FDA since 1992 to improve access to treatments for life-threatening diseases such as cancer, they suggested.

As part of that process, the Duke researchers pointed out, early-phase clinical trials often measure goals other than improved survival.

“An inherent tension arises between the desire to use new, life-saving treatments and the imperative to develop the evidence that patients, clinicians, regulatory agencies and advocacy groups need to make sound decisions,” Hirsch commented.

“Unfortunately, the high prevalence of small studies that lack rigour [in oncology] limits the ability to assess the evidence supporting specific treatments.”

Incidence and volume

The analysis also highlighted some disparities between the incidence and mortality of some cancer types, and the volume of clinical research being conducted in those indications.

For example, lung cancer has the highest incidence of all cancers, with 14.5% of all new diagnoses and 27.6% of all cancer deaths in 2010. Yet only 9.2% of studies on focused on lung cancer, the Duke researchers observed.

By contrast, lymphoma was the focus of 6.6% of studies on the register, yet it accounts for 4.8% of all cancer cases and 3.8% of deaths.