ESTRO 2023 - Abstract Book

S98

Saturday 13 May

ESTRO 2023

1 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus , Denmark; 2 Amsterdam University Medical Centers, University of Amsterdam, Department of Radiotherapy , Amsterdam, The Netherlands; 3 Haukeland University Hospital , Department of Oncology, Bergen, Norway; 4 Regina Elena National Cancer Institute, ., Rome, Italy Purpose or Objective The ESHO protocol 1-85 is a international multicenter randomized trial initiated by the European Society for Hyperthermic Oncology with the aim to investigate the value of hyperthermia (HT) as an adjuvant to radiotherapy (RT) in treatment of locally advanced breast carcinoma. The trial is one of the largest studies of hyperthermia in radiotherapy but has not been Between February 1987 and November 1993, 155 tumors in 151 patients (4 patients had simultaneous bilateral tumors). Tumors were stratified according to institution and (T2-3/T4) and randomly assigned to receive radiotherapy alone (2 Gy/fx, 5 fx/wk) to a total dose of 65-70 Gy, incl. boost, or the same radiotherapy followed once weekly by hyperthermia (aimed for 43 °C for 60 min). Radiation was given with high voltage photons or electrons. The primary endpoint was persistent complete response in the treated area. Results A total of 147 tumors in 143 patients were evaluable, with a median observation time of 21 (range 1-134) months. Seventy tumors were randomized to RT alone and 77 to RT+HT. Size was T4 in 92, and T2-3 in 55 tumors, respectively. The compliance to RT was good with all but 12 pts fulfilling the planned RT treatment. The tolerance to HT fair, but associated with moderate to severe pain and discomfort in 15% of the treatments. In 83% of the heated patients a least one heat treatment achieved the target temperature, but the temperature variations was large. Addition of heat did not significantly increase the acute nor late radiation reactions. Overall, the 5-year actuarial local failure rate 57%. Univariate analysis showed a significant influence of hyperthermia (RT alone 66% versus RT+HT 48%, p = 0.011, see figure 1) and T- (T4 72% versus T 2-3 35%, p = 0.003). A Cox multivariate analysis showed the same factors to be the only significant prognostic parameters: hyperthermia (HR: 0.58 [0.36-0.94], p = 0.02) and tumor (odds ratio: 0.49 [0.29-0.83], p = 0.006). Consequentially, more patients given RT+HT (38%) survived without disease (DFS), than after RT alone (20%), p = 0.019) Conclusion A randomized multicenter trial investigating the addition of a weekly hyperthermia treatment to radiotherapy of patients with locally advanced breast cancer significantly enhanced the 5-year tumor control and yielded more patients surviving free from cancer. The results of this Phase III prospective multicenter randomized trial substantiate the potential clinical benefit of hyperthermic oncology. previously published. Materials and Methods

MO-0136 Single Pre-Operative Radiation Therapy (SPORT-CK) trial for low-risk breast cancer: A Phase 2 study D. Mahmoud 1 , L. Alvarado 1 , S. Meterissian 2 , D. Anderson 2 , C. Lambert 1 , F. Tremblay 2 , V. Panet-Raymond 1 , D. Fleiszer 2 , J. Keyserlingk 2 , N. Otaky 3 , A. Loutfi 2 , M. David 1 , M. Duclos 1 , A. Saidi 1 , P. Ramia 1 , M. Yassa 4 , T. Hijal 1 1 McGill University Health Centre, Division of Radiation Oncology, Montreal, Canada; 2 McGill University, Department of Surgery, Montreal, Canada; 3 McGill University , Department of Surgery, Montreal, Canada; 4 Hopital Maisonneuve Rosemont, Division of Radiation Oncology, Montreal, Canada Purpose or Objective Pre-operative partial breast irradiation (PBI) is a novel technique that can be used in patients with early-stage breast cancer with the goal of limiting the irradiated breast volume and toxicity. The aim trial is to assess the toxicity, surgical complications, and oncologic and cosmetic outcomes of pre-operative PBI. Materials and Methods In this single-centre phase II, single-arm trial, we enrolled elderly women (age ≥ 60), with unifocal low-risk, early-stage breast invasive ductal carcinoma (cT1N0, grade 1 and 2, ER positive, Her2 negative, without LVI on biopsy). Patients were treated with 20 Gy in 1 fraction of pre-operative PBI using volumetric modulated arc therapy (VMAT). Patients then underwent breast-conserving surgery (BCS) +/- sentinel lymph node biopsy within 72h from radiation. Patients with positive surgical margins underwent margin re-excision. Adjuvant whole breast or locoregional irradiation was indicated for several unexpected pathologic findings such as tumour > 3cm, grade 3 disease, positive lymph nodes, pure lobular pathology or if