ESTRO 2020 Abstract Book

S150 ESTRO 2020

Netherlands Antilles ; 2 Erasmuc MC, Radiation Oncology, Rotterdam, Netherlands Antilles ; 3 LUMC, Radiation Oncology, Leiden, Netherlands Antilles Purpose or Objective Hyperthermia therapy (HT), heating tumors to 40-45°C, is a known radiotherapy and chemotherapy sensitizer. The additional benefit of HT to re-irradiation (re-RT) for loco- regional recurrent breast cancer has been proven in multiple randomized trials. However, the efficacy of re- RT+HT varies widely. We performed a systematic review to investigate whether there is a relationship between achieved HT dose, tumor response and thermal toxicity for patients with recurrent breast cancer treated with re- RT+HT. Material and Methods Four databases, EMBASE, PubMed, Cochrane library and clinicaltrials.gov, were searched with the terms breast, radiotherapy, hyperthermia therapy and their synonyms. Final search was performed on April 3 rd 2019. The search was not limited to any date, both articles and conference proceedings were allowed, a filter for English articles and human studies was applied. Articles were excluded when the relationship between hyperthermia dose and outcome in patients with breast cancer was not analyzed, less than 10 patients or lesions were reported, concurrent chemotherapy or drugs were given or when articles were updated in a later publication by the same author(s). Results A total of 1249 articles were identified through the search and were screened. Twenty-two articles were included in the systematic review, reporting on 2330 patients with breast cancer treated with re-RT+HT. In total, thirty-two different HT dose parameters were tested for a correlation with tumor response and thermal toxicity. Thermal dose showed a significant correlation with clinical complete response in 10/15 studies, in 10/13 studies for duration of local control, in 2/2 studies for overall survival and in 7/11 studies for thermal toxicity. Patients who received a high thermal dose, had on average 34% (range 27-53%) more complete responses than patients who received a low thermal dose. Low dose hyperthermia combined with RT is comparable to RT alone (Figure 1). The incidence of thermal toxicity increased with higher maximum skin temperature. Patients who achieved higher HT dose had increased odds/ probability on improved clinical outcome and on thermal toxicity.

patient is shown in Figure 1. Evaluation metrics were calculated for all five test patients and average values (± SD) of all these parameters are shown in Table 1.

Figure 1: An example of autosegmented structures for one patient. The filled structure is manual referense delineation. Table 1: Average (± SD) values of evaluation metrics (DSC, Jac, VS, BF, HD and Ave) of autosegmented CTV Breast, Heart, Left Lung and LAD structures for five test patients. Five different software was used for autosegmentation (ABAS, Mirada, MIM, Eclipse and MVision).

Conclusion Performance of autosegmentation software was similar for CTV breast, lung and heart structures. In terms of Ave metric, all software segmented CTV structures were within 5 mm compared to manual reference delineation. More variation was detected in the autosegmentation of LAD between the software. Even though the number of patients in the training set was limited, AI method resulted equal or better contours as compared to atlas based methods.

PD-0292 Breast cancer patients with brain metastases: A multicenter retrospective study (KROG 16-12)

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Figure 1. The beneficial effect of hyperthermia therapy (HT) when added to radiotherapy (RT) may require a high HT dose in patients with locoregional recurrent breast cancer. Data from Datta et al. (2016) are compared to the results of this review. Conclusion

PD-0293 The benefit of high hyperthermia dose in re- irradiation of loco-regional recurrent breast cancer. A. Bakker 1 , J. Van der Zee 2 , G. Van Tienhoven 1 , H.P. Kok 1 , C.R.N. Rasch 3 , H. Crezee 1 1 Amsterdam UMC, Radiation Oncology, Amsterdam,