Patient population analysis in EORTC trial 22881/10882 on the role of a booster dose in breast-conserving therapy.

The changing composition of the patient population in breast cancer, which has been reported over the last decade, has important consequences for prognosis. In the present trial, an analysis of the population in an EORTC trial (22881/10882) on breast-conserving therapy was conducted. A shift towards earlier stages has been seen stage per stage, therefore better survival and local control rates are likely to be expected in comparison to previously published series. The majority of tumours in this trial were small, with a median clinical size of 2 cm and a median pathological size of 1.5 cm. A substantial number of lesions were detected in a pre-clinical stage (17.8%). Nodal involvement was present in only 19% of all patients and usually in only a low number of nodes (only 4% of all patients had four or more nodes invaded). The median number of nodes examined was 12, the difference between institutions was large. There was a significant correlation between the number of nodes examined, the percentage of patients with positive nodes (P = 0.03) and the percentage of patients with massive axillary invasion (P = 0.003). The correlation between clinical evidence and pathological invasion of the axillary nodes showed that 15% of the clinical examinations were false-negative and 51% were false-positive. Pathological nodal invasion could be clinically predicted in only 31% of patients, and consequently clinical examination of the axilla was a poor predictor of prognosis in this study. Pathological invasion of axillary lymph nodes was better correlated to pathological tumour size than clinical or radiological size.

Radiation dose homogeneity in an EORTC multicenter trial on breast irradiation.

The influence of the radiation dose on local control and cosmetic outcome in breast-conserving treatment for breast cancer is investigated in EORTC trial 2288110882. In this study 50 Gy is administered to the whole breast, and 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 homogeneity of the radiation dose as reported in the first 1915 treatment forms, received at the EORTC Data Center. The dose to the prescription Point (A) was within 95 and 110% of 50 Gy in all but 13 (99.3%) patients (median dose 50 Gy) 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 dose 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 doses, despite a number of ambiguities in the protocol, which were efficiently clarified a few months after the beginning of the trial. This high level of consistency is a remarkable achievement given the number of centers, the number of patients, and the number of countries involved in this trial.