Until 10/2005, 1109 unselected patients of any risk group have been identified among seven centers using identical methods, sequencing and dosage for intra- and postoperative radiotherapy. A median IOERT dose of 10 Gy was applied (90 % reference isodose), preceding WBI with 50-54 Gy (single doses 1.7-2 Gy).
At a median follow up of 72.4 months (0.8-239), only 16 in-breast recurrences were observed, yielding a local tumor control rate of 99.2 % . Relapses occurred 12.5-151 months after primary treatment. In multivariate analysis only grade 3 reached significance (p = 0.031) to be predictive for local recurrence development. Taking into account patient age, annual in-breast recurrence rates amounted 0.64 % , 0.34 % , 0.21 % and 0.16 % in patients <40 years; 40-49 years; 50-59 years and ?60 years, respectively.
In all risk subgroups, a 10 Gy IOERT boost prior to WBI provided outstanding local control rates, comparing favourably to all trials with similar length of follow up.