Quality control of involved-field radiotherapy in patients with advanced Hodgkin's lymphoma (EORTC 20884)

To evaluate the impact of the quality of involved-field radiotherapy (IFRT) on clinical outcome in patients with advanced Hodgkin's lymphoma (HL) in complete remission (CR) after six to eight cycles of mechlorethamine, vincristine, procarbazine, prednisone-doxorubicin, bleomycin, and vinblastine (MOPP-ABV) chemotherapy.

A retrospective review of clinical and radiologic data, radiation charts, simulator films, and megavoltage (MV) photographs was performed. IFRT consisted of 24 Gy to all initially involved nodal areas and 16-24 Gy to all initially involved extranodal sites. Major violations were defined as no or only partial irradiation of an originally involved area, or a total dose <90% of the prescribed dose.

Of the 739 patients who were enrolled in the trial between 1989 and 2000, 57% achieved a CR; 152 of 172 patients randomized to IFRT actually received radiotherapy; and in 135 patients, quality control was performed. The overall major violation rate was 47%, predominantly concerning target volumes. The total dose was correct in 81% of the patients. After a median follow-up of 6.5 years, there was no difference in cumulative failure rate between patients with or without major violations. There was no relationship between incidence or site of relapse and major protocol violations.

In advanced-stage HL patients in complete remission after six to eight cycles of MOPP-ABV, the outcome was not influenced by violation of the radiotherapy protocol.