Impact of initial quality control review on study outcome in lung and head/neck cancer studies--review of the Radiation Therapy Oncology Group experience.

The Radiation Therapy Oncology Group (RTOG) initiated cooperative clinical trials in 1971. In 1978, RTOG developed a formalized program of Quality Control (QC) divided into initial and final phases. The initial review process consisted of two steps. The first phase of review is an evaluation performed by a radiation oncologist to verify treatment plan and field borders. The second portion of the initial review process originally consisted of dosimetry calculation verification based on machine data provided by the regional Radiological Physics Center and treatment planning data provided by the accessioning institution. Between 1978 and December 31, 1987, a total of 11,343 cases in 96 RTOG protocols, excluding particle studies, underwent initial review. Of this number, 2227 patients were entered in lung cancer studies and 1341 patients were entered in head/neck cancer studies. Initial review was carried out in 2089 (93.8%) of the lung cancer cases. Missing or delayed data accounted for 138 (6.2%) cases not reviewed initially. In head/neck cancer trials, 1251 (93.2%) received initial review and 90 (6.8%) did not. Our findings suggest that there are sharply defined but long lasting learning experiences involved in clinical trial participation. Consideration may be given to modifying the initial review process to use random sampling of cases accessioned by experienced investigators in ongoing clinical trials and to continuing the total case evaluation on all new studies and cases entered by inexperienced investigators or investigators/institutions with unsatisfactory performance. Recommendations regarding initial review of other sites will await evaluation of the impact of initial review on those sites.