ESTRO 2023 - Abstract Book

S1012

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ESTRO 2023

IORT was performed by a 9 MeV electron beam Novac 7 linac. The prescribed dose was 21 Gy at 90 % isodose. The median follow up is 16 years and all patients with at least three follow up or an event are enclosed in the analysis. The analysed endpoints are Intra Breast Relapse Free Survival (IBRFS), Disease Free Survival (DFS), Cancer Specific Survival (CSS), Overall Survival (OS), Metastases Free Survival (MFS). The 5, 10 and 15 years cumulative survivals compared according to adherence or violation of the new eligibility criteria are summarised in the table. The survival curves are shown in the figures. Results Observed local relapses are 126 (70 in field, 50 out-field, 6 n.o.s.), corresponding to a crude rate of 14%. Despite it could be likely that outcome is affected also by prognostic factors not only by the technique, the higher incidence of metastases is not otherwise explained, the analysis shows that all endpoints are highly dependent on compliance with the eligibility criteria, a slight deviation from them definitely worsen the prognosis.

98.5 89.8 81.6

IBRFS (%) fully fulfilled / not fulfilled

not fulfilled

91.8 81.7 72.8 p=0.0024

99.0 97.5 94.6

DFS (%) fully fulfilled

not fulfilled

92.6 84.7 80.9 p<0.0001

99.5 98.1 96.8

CSS (%) fully fulfilled

not fulfilled

97.3 93.8 90.8 p=0.00176

97.3 90.8 83.9

OS (%) fully fulfilled

not fulfilled

93.0 84.1 71.8 p=0.0144

99.0 97.5 95.1

MFS (%) fully fulfilled

not fulfilled

94.4 86.2 79.4 p=0.0001

Conclusion At the moment the IORT gained great appeal among women and surgeons for early breast cancer but it is still encumbered by high risk of local relapse if patients are not strictly selected. Also overall and cancer specific survival seems to be affected by the deviation from inclusion criteria, fulfilling all of them is of paramount importance.

PO-1267 Accelerated fractionation in breast cancer. Results in our institution

A. Calvo Tudela 1 , M.J. Garcia Anaya 1 , S. Segado Guillot 1 , N. Martin Romero 1 , I. Garcia Rios 1

1 Virgen de la Victoria University Hospital, Radiation Oncology, Malaga, Spain

Purpose or Objective