ESTRO 2023 - Abstract Book

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ESTRO 2023

The interim analysis was planned after inclusion of 50 patients. Patients who did not answer any questionnaires after baseline were categorized as non- responders, the rest as responders. We assessed how many patients completed 5- and 9 weeks follow-up (timepoints of primary endpoint analysis). Results The interim was carried out in September 2022 after inclusion of 88 patients. 81 patients were included in the analysis, Figure 1 and Table 1. A total of 39 (52%) patients completed 5 weeks follow-up and 33 patients (40%) completed 9 weeks of follow-up. As many as 35 patients (43%) were non-responders. Non-responders had a significantly worse performance status (p=0.0006) and 90 day mortality was 46% compared to 9% in responders.

Conclusion With the current compliance rate, the total number of evaluable patients will be too low, and the study under-powered. The low response rate can be explained by the fragile patient population with rapid decline in performance and short overall survival. To increase compliance, we have introduced electronical SMS-questionnaires, weekly reminders by telephone and a possibility of telephone guidance 2-3 times weekly. If this does not increase compliance considerably, an increased number of participants is needed.

PO-1087 Use of breast cancer ultra-hypofractionated radiation treatments during and post COVID19 pandemic

-. -caudrelier 1 , K. Lekx-Toniolo 2 , C. Hache 3 , S. Comino 3

1 The Ottawa Hospital Cancer Centre, radiation Medicine, Ottawa, Canada; 2 The Ottawa Hospital Cancer Centre, Medical Physics, Ottawa, Canada; 3 The Ottawa Hospital Cancer Centre, Radiation Medicine, Ottawa, Canada Purpose or Objective To evaluate the changes of breast cancer radiation treatments fractionation, in a Canadian comprehensive cancer center over the COVID19 pandemic time, when actions have been taken to mitigate infection risks. The number of radiotherapy sessions freed from Linac will be estimated.

Materials and Methods