S346
Clinical - Breast
ESTRO 2026
Contact X-ray machine was designed to produce a 50 kVp beamwith a high dose rate ≥ 15 Gy/minute. A pilot study with the first prototype wasconducted in Nice (1). Five-years results are presented Material/Methods: Women aged ≥ 60 years with unifocal ductal breastadenocarcinoma ≤ 2.5 cm pN0, grade 1-2 were included. Surgical local excision withsentinel node dissection was performed and the applicator was placed in the tumorbed after excision with a prescribed dose of 20 Gy at the applicator surface. The main endpoint of the study was the doses measured with the Gafchromic films at the skin andin the excision cavity; Secondary endpoints were application quality, early toxicity andrelapse free survival. Results: Between 10/2018 and 09/2019, 26 patients were included with a medianage of 73 years (61-90). Mean Gafchromic doses were 18.8 Gy ± 2 Gy at the southpole, 15.6 Gy ± 2.81 Gy at the equator and 2.5 Gy ± 1.67 Gy at the skin. Quality ofapplicator positioning was excellent in 91,7% of the cases. No skin or subcutaneoustoxicity > grade 2 were observed during the first 12 months after intra operativeradiation therapy. At 4 years, one patient who received additional external radiationtherapy (EBRT) experimented a breast radionecrosis grade 4. With a median followup of 61.1 months, we observed one early local relapse, one regional relapse andone metastatic relapse (permeation nodules in the treated breast) : the patient withearly local relapse had a lobular carcinoma with a restricted tumor margin and nosalvage EBRT ; the patient who experienced a regional nodal axillary failure was 63at the inclusion ; and finally, the patient who presented a metastatic relapse had apositive tumor margin, was 90 years old and considered unfit for further treatment. Conclusion: This was the first phase II study testing the Papillon + tm system forbreast IORT with in vivo dosimetry measurements. The RPOS+2 trial is currentlyongoing at Centre Antoine Lacassagne (Nice) with more restrictive criteria in theinclusion (age ≥ 65, tumor size ≤ 2cm, exclusive in situ carcinoma excluded) and asystematic indication of EBRT in case of unfavoralable histological criteria. References: (1) ME Chand (CTRO-2023) Keywords: Breast IORT, Papillon + system, High dose rate
the patients population are listed in Table 1.Most of the patients enrolled had as additional risk factor surgical margin < 4 mm (29, 32.0%).Among patients with unfavourable biology (55, 61%), 47(85%) patients presented with luminal B tumors, 6 patients (11%) with triple negative and 2 (4%)with HER2 +tumors. Median follow-up time was 24 months (range:6-65 months).59 (65%)patients had a follow-up longer than one year.All patients completed treatment to the prescribed dose. All patients were evaluable for acute adverse events.No patients experienced grade ≥ 2 acute side effects, only 1patient (1%) experienced G2 subacute side effect (breast edema). Table 1 and 2 summarize results on adverse events.
Conclusion: Acute and subacute adverse events was low in this cohort of patients. Longer follow-up is required to report the primary endpoint and efficacy data. Keywords: breast cancer, radiotherapy, simultaneous boost
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Intraoperative radiotherapy for breast cancer using the papillon+ system: 5-year results update Flora Courtault-Deslandes 1 , Syrine Ben Dhia 1 , Jocelyn Gal 2 , Yann Chateau 2 , Maud Le Guyader 1 , Marie Eve Chand Fouche 1 , Catherine Dejean 3 , Yassine Rizzi 3 , Mathieu Gautier 3 , Yann Delpech 4 , Jean-Pierre Gerard 1 , Emmanuel Barranger 4 1 Radiation Oncology, Centre Antoine Lacassagne, Nice, France. 2 Epidemiology/Biostatistics, Centre Antoine Lacassagne, Nice, France. 3 Medical Physics, Centre Antoine Lacassagne, Nice, France. 4 Breast and Gynecological Surgery, Centre Antoine Lacassagne, Nice, France Purpose/Objective: Breast intra operative radiation therapy (IORT) has beenevaluated with different systems delivering 20-21 Gy with treatment times around 30min. Papillon + TM
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