The influence of patient, tumor and treatment factors on the cosmetic results after breast-conserving therapy in the EORTC 'boost vs. no boost' trial. EORTC Radiotherapy and Breast Cancer Cooperative Groups

To analyze the influence of different patient, tumor, and treatment parameters on the cosmetic outcome after breast-conserving therapy at 3-year follow-up. A subjective and an objective cosmetic scoring method was used and the results of both methods were compared. In EORTC trial 22881/10882, 5569 early-stage breast cancer patients were treated with tumorectomy and axillary dissection, followed by tangential fields irradiation of the breast to a dose of 50 Gy in 5 weeks, at 2 Gy per fraction. A total of 5318 patients, having a microscopically complete tumorectomy, were randomized between no further treatment and a boost of 16 Gy to the primary tumor bed. The cosmetic result at 3-year follow-up was assessed by a panel for 731 patients, and by digitizer measurements, measuring the displacement of the nipple, for 1141 patients. Univariate and multivariate analyses were used to evaluate the correlation between various patient, tumor, and treatment factors and cosmesis. The factors associated with a worsened cosmesis according to the panel evaluation were: an inferior tumor location, a large excision volume, the presence of postoperative breast complications, and the radiotherapy boost. According to the digitizer measurements, a central/superior tumor location, a large excision volume, an increased pathological tumor size, an increased radiation dose inhomogeneity, and an increased bra cup size resulted in an increased asymmetry in nipple position. It appeared that the evaluation of the nipple position (whether by panel or by digitizer) is only moderately representative of the overall cosmetic outcome. To achieve a good cosmesis, it is necessary to excise the tumor with a limited margin, to avoid postoperative complications, to assess the need for a boost in the individual patient, and to give the radiation dose as homogeneously as possible. As far as the method of evaluation is concerned, the panel evaluation is the most appropriate method for giving an overall impression of the cosmetic result after breast-conserving therapy (BCT). The use of the digitizer is recommended for comparing the cosmetic outcome of two different approaches to BCT or for analyzing cosmetic changes over time.