Randomized controlled trials on PET: a systematic review of topics, design, and quality

Randomized controlled trials (RCTs) add important information to diagnostic accuracy studies in the evaluation of PET and PET/CT. We evaluated how many RCTs on PET existed, which clinical topics they addressed, and what their design and quality were.

We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (Clinical Trials) up to August 2010. We also searched in ClinicalTrials.gov and the International Clinical Trials Registry Platform for ongoing RCTs up to March 2011. Titles and abstracts and full texts were screened independently by 2 reviewers. Study characteristics were extracted with standard extraction sheets for ongoing and published RCTs, and risk of bias was assessed for published ones.

We identified 54 RCTs, 12 of which were published. The main topics in published studies were non-small cell lung cancer and colorectal cancer; only 3 were conducted in nononcologic fields (this trend was similar in ongoing studies, in which the most common topic was Hodgkin disease). The main indications in the oncologic PET studies were staging in published studies and restaging (mostly including an early assessment of treatment response) in ongoing ones. All except 1 of the published studies applied a marker-based strategy design, whereas about 43% (18/42) of ongoing studies use a more efficient design (Enrichment Design or Marker by Treatment Interaction Design).

A relatively high number of ongoing RCTs of PET in several oncologic fields are expected to produce robust results over the next few years. For nononcologic topics, further high-quality studies are still needed to ascertain the benefit of this technique for patients. As funding is usually difficult in nondrug topics, alternative concepts of funding, which should also involve the manufacturers of diagnostic devices, but also more efficient study designs, should be applied to bridge the evidence gap on PET in the near future.