The successful contribution by the Trans-Tasman Radiation Oncology Group to intergroup radiation oncology trials (2010-2012) and a proposal for accrual definitions

A recent Trans-Tasman Radiation Oncology Group (TROG) report reviewed accrual to TROG-sponsored trials but did not include intergroup trials. To analyse radiation oncology trials, some terminology needed to be defined because some terms are used interchangeably, including "accrual", "enlistment", "enrolment" and "recruitment", and there were no standard definitions. The report defined actual and expected accrual rates (AAR and EAR) and the ratio of these (RAEAR). The EAR was defined as the accrual that was likely to occur based on factors known prior to the trial. The AAR is determined as the trial proceeds and may take time to stabilize. "Projected Accrual" is a linear extension of the actual accrual curve. The TROG report indicated that the mean AAR to TROG-sponsored (defined here as "Type A") trials was 0.67 of the EAR and that the AAR took about 7 months to become stable. TROG also contributes to trials sponsored by other trials groups ("Type B" trials). The most common collaborators are European (ESTRO - the European Society for Radiotherapy and Oncology) and Canadian (NCIC - National Cancer Institute of Canada). Individual TROG members usually bring Type B trials to the TROG meeting as new proposals and each Type B proposal has been subject to the same processes in obtaining approval as Type A proposals, often consuming a significant portion of the accrual period before the TROG contribution can begin.