Radiation dose homogeneity in an EORTC multicenter trial on breast irradiation

The influence of the radiation dose on local control and cosmetic outcome i n breast-conserving treatment for breast cancer is investigated in EORTC tr ial 22881/10882. In this study 50 Gy is administered to the whole breast, a nd the effect of an additional dose to the tumor-bearing area (boost dose) is evaluated. The purpose of this analysis is to document the dose homogene ity of the radiation dose as reported in the first 1915 treatment forms. re ceived at the EORTC Data Center. The dose to the prescription Point (A) was within 95 and 110% of 50 GS in all but 13 (99.3%) patients (median dose 50 GS.) and the minimum and maximum doses in the central plane of the breast were within 95% and 110% of the dose to point A in 82% of patients. The dos e to the tumor excision area (point B) was within the homogeneity criteria in 97% of patients, and the boost doses were consistent with randomization in 93% of cases. These data, based on one-third of the randomized patients in trial 22881/10882 demonstrate a high level of homogeneity in radiation d oses, despite a number of ambiguities in the protocol, which were efficient ly clarified a few months after the beginning of the trial. This high level of consistency is a remarkable achievement given the number of centers, th e number of patients. and the number of countries involved in this trial.