ESTRO 36 Abstract Book

S627 ESTRO 36 _______________________________________________________________________________________________

control, including patients treated with BCS and MRM, between November 2012 and March 2016. Material and Methods We included 560 patients: 394 were treated with MRM and 166 with BCS. According to the radiotherapy schedule received, they were divided in 3 groups: 40Gy/15Fx, 42Gy/16Fx, and 50Gy/25Fx. Results At the end of the treatment, acute skin morbidity grade 1 was found in 57, 72 and 32% of the cases; grade 2 in 42, 27 and 64% for treatments with 40, 42 and 50 Gy, respectively, and grade 3 in 3% for a dose of 50 Gy in patients treated with MRM. Regarding BCS, skin morbidity grade 1 was found in 48, 66 and 23% of the cases, while grade 2 in 51, 33 and 73% for treatments with 40, 42 and 50 Gy, respectively, and grade 3 in 3% of patients treated with 50 Gy (Figure 1). After the first month, morbidity was reported in 489 patients (341 MRM and 148 BCS); mainly xerosis and hyperpigmentation; subacute morbidity (at third month) was reported in 346 patients (247 of MRM group and 99 of BCS group), mainly xerosis (Table 1). In follow-up studies, radiation pneumonitis was found in seven patients treated with MRM (2.8% of the total), regardless of the schedule received; they were still asymptomatic in the last follow-up. So far, we have an average 6-month follow-up after ending RT treatment with 226 patients (136 of them were treated with MRM, and 90 with BCS), with a maximum 3-year follow-up. In total, nine locoregional recurrences (LR) are reported, either on the chest wall, breast or the lymph node regions, while we found 14 systemic recurrences which are reported in one or more sites. Most LR were observed among patients treated with MRM, which may be associated with the patients undergoing radical treatments that generally have a more advanced clinical stage. Conclusion With these results we can conclude that it is safe to use hypofractionated treatments for patients with breast cancer treated either with MRM , with acute and subacute morbidity similar to that found in patients treated with conventional schedules, at least with a similar local control between the different schedules. It is required, however, to complete the long-term monitoring. EP-1154 Changes in skin microcirculation during radiation therapy for breast cancer E. Tesselaar 1 , A.M. Flejmer 2 , S. Farnebo 3 , A. Dasu 4 1 Linköping University, Department of Radiation Physics and Department of Medical and Health Sciences, Linköping, Sweden 2 Linköping University, Department of Oncology and Department of Clinical and Experimental Medicine, Linköping, Sweden 3 Linköping University, Department of Hand and Plastic Surgery and Burns and Department of Clinical and Purpose or Objective The majority of breast cancer patients who receive radiation treatment are affected by acute radiation- induced skin changes that are usually assessed by subjective methods, like Radiation Therapy Oncology Group (RTOG) scoring. These methods complicate the comparison between treatments or patient groups and therefore objective and robust methods are needed to assess acute skin reactions. This study investigates the feasibility of new camera-based methods for monitoring Experimental Medicine, Linköping, Sweden 4 Skandionkliniken, ----, Uppsala, Sweden

skin microcirculation to objectively assess and quantify acute skin reactions during radiation treatment. Material and Methods Fifteen patients undergoing adjuvant radiation therapy for breast cancer were included in the study. The patients received 42.56 Gy in 16 fractions using three dimensional conformal radiotherapy with tangential photon irradiation. Radiation-induced changes in microvascular perfusion and red blood cell (RBC) concentration in the skin of the patients were quantified with laser Doppler flowmetry, laser speckle contrast imaging and polarized light spectroscopy imaging. Measurements were made before treatment, once a week during treatment and directly after the last fraction. Changes in measured values were analysed with two-way analyses of variance with Dunnett’s correction for multiple comparisons. Results Perfusion (Figure 1) and RBC concentration (Figure 2) were increased in the treated breast after 1-5 fractions, with largest effects in the areola and the medial area. No changes in perfusion and RBC concentration were seen in the untreated breast. In contrast, RTOG scores were increased above 0.5 only after two weeks of treatment. Correlations have also been found between perfusion (r=0.52) and RBC concentration (r=0.59) measurements performed during current week and the RTOG score in the following week. Furthermore, a good correlation has been found between perfusion, as measured with LSCI, and relative RBC concentration (r=0.64). Clinically, the results indicate that optical techniques could be used for early assessment of skin changes, with RBC concentration the better predictor.

Figure 1. Variation of capillary perfusion in irradiated skin of breast cancer patients