The development of quality assurance programs for radiotherapy within the German Hodgkin Study Group (GHSG). Introduction, continuing work, and results of the radiotherapy reference panel.

BACKGROUND AND
PURPOSE: The German Hodgkin Study Group (GHSG), including more than 500 participating centers, established a central radiotherapy (RT) reference center to improve quality of treatment, starting with the first study generation in 1978. More than 11,000 patients with Hodgkin's lymphoma (HL) have been enrolled into these trials. Extensive continuing quality assurance programs (QAPs) during the study generations have been performed. The purpose of the present article is to summarize the experiences and results of the performed and ongoing QAPs.
MATERIAL AND METHODS: A panel of expert radiation oncologists (second study generation HD4-6, 1988-1994, and third study generation HD7-9, 1993-1998) retrospectively evaluated the adequacy of treatment fields, applied radiation doses, treatment time, and technical parameters. Furthermore, a detailed analysis of relapses in correlation with the performed RT was conducted. For the fourth study generation (HD10-12, 1998-2002), the RT reference center changed from Munich to Cologne. New RT QAPs were initiated according to the demands of the new trials and former programs were enhanced: (1) central prospective radiation oncologic review of cross-sectional imaging (HD10, HD11) to create the individual radiation treatment plan; (2) retrospective analysis of the adequacy of the performed involved-field (IF) RT (HD10, HD11); (3) the multidisciplinary HD12 panel (radiation oncologists, medical oncologists, diagnostic radiologists); (4) initiation and integration of a teleradiotherapy network into the GHSG trials.
RESULTS: A strong achievement of these activities in the era of extended-field RT was to show that major deviations of radiation treatment portals and radiation dose from prospective treatment prescriptions revealed to be unfavorable prognostic factors for patients with early-stage HL (HD4). The central prospective radiation oncological review of all diagnostic imaging (HD10, HD11) showed that corrections of disease involvement in 49% of patients (593/1,214) with early stages (HD10) and in 67% of patients (936/1,397) with intermediate stages (HD11) were necessary. These procedures had a significant impact on the correctness of stage definition, allocation to treatment groups and on the extension of the IF treatment volume. Until now, 1,080 patients in HD10 and HD11 have been evaluated retrospectively with regard to the adequacy of the performed IF-RT. Although the participating institutions got a precise RT prescription, interim results reveal deviations in a significant number of cases. In the HD12 trial (advanced stages), a multidisciplinary panel of radiation oncologists, radiologists and medical oncologists reviewed all the diagnostic imaging from diagnosis throughout the treatment in comparison to the documentation forms. For patients with poor response to chemotherapy, the panel recommended RT independent of the randomization. This procedure ensured that patients with a poor response to chemotherapy received additional RT. 1,080 of 1,594 randomized patients (68%) could be analyzed. After chemotherapy, 599 patients (56%) showed residual disease (> 1.5 cm), and in 145/1,080 patients (13.5%) the panel recommended additional RT independent of the randomization arm. The introduction of electronic image transfer optimized and simplified the workflow of the QAPs. Rapid online consultation and real-time teleconferences regarding disease involvement, patient management and communication of the RT prescription with connected hospitals proved to be extremely helpful.
CONCLUSION: Today, radiation oncologists in the GHSG perform a continuous and efficient QAP to improve treatment quality of study patients. For early favorable and unfavorable HL a central prospective review of all diagnostic imaging is performed by expert radiation oncologists to control the disease extension and to define the IF treatment volume. Retrospective analysis of RT portals by an expert panel detects faults in the applied irradiation. Participants are trained on the definition of IF-RT by workshops on the occasion of annual GHSG meetings and on the annual meetings of the German Society of Therapeutic Radiation Oncology (DEGRO). For the advanced stages a multidisciplinary panel evaluates the treatment response to chemotherapy. Patients with a poor response receive additional RT due to the panel's recommendation. The introduction of teleradiotherapy into the GHSG trials improves the dialogue between the central RT reference center and study participants and thus contributes to high RT quality for study patients.