The potential impact of treatment variations on the results of radiotherapy of the internal mammary lymph node chain: A quality-assurance report on the dummy run of EORTC phase III randomized trial 22922/10925 in stage I-IIIbreast cancer

Purpose: To present the results of the dummy run of the European Organizati on for Research and Treatment of Cancer (EORTC) trial investigating the rol e of adjuvant internal mammary and medial supraclavicular (IM-MS) irradiati on in Stage I-m breast cancer. Methods and Materials: All participating institutions were asked to produce a treatment plan without (Arm 1) and with (Arm 2) simultaneous IM-MS irrad iation of 1 patient after mastectomy and of 1 patient after lumpectomy. Thi rty-two dummy runs have been evaluated for compliance to protocol guideline s, with respect to treatment technique and dose prescription. Results: A number of more or less important deviations in treatment setup a nd prescription have been found. The dose in the IM-MS region deviated sign ificantly from the prescribed dose in 10% of the cases for Arm 1, and in 21 % for Arm 2. Assuming a true 5% 10-year survival benefit from optimal IM-MS irradiation, an increase of only 3.8% will be found due to this suboptimal dose distribution. Conclusion: In the dummy run, a number of potential systematic protocol dev iations that might lead to false-negative results were detected. By providi ng recommendations to the participating institutions, we expect to improve the interinstitutional consistency and to promote a high quality irradiatio n in all institutions participating in the trial. (C) 2001 Elsevier Science Inc.