ESTRO 2025 - Abstract Book

S619

Clinical - Breast

ESTRO 2025

d 50(82%) patients, respectively. Mean tumor size was 10.5 cm (2.4-26 cm). Margins were involved and close in 14(23%) and 20(33%), respectively. Skin and nipple areola complex involved in 10(16%) and 5(8%) patients, respectively. Adjuvant radiation was delivered in 46(75%) patients. Radiotherapy dose was 34Gy/10#/2wks, 35Gy/15#/3wks, 40Gy/15#/3wks, 45Gy/20#/4wks and 50Gy/25#/5wks in 3(6.5%), 7(15%), 14(30%), 17(37%) and 5(11%) patients, respectively. Boost was delivered in 12(33%), dose 8-15Gy in 2-5 fractions. Biopsy at recurrence was benign, borderline, and malignant in 13(36%), 4(11%), and 19(53%) patients, respectively. On re-excision pathology was borderline and malignant in 6(17%) and 30(83%) patients, respectively. Mean tumor size was 11 cm (2.4-23 cm). Margins were positive in 2(6%) patients and <5mm in 14(39%) patients. Skin was involved in 2(6%) patients. 7(19%) patients recurred for the 3 rd time. Metastases occurred in 7(%) patients. Most common site of metastases was lung 7(11%), brain 3(5%) and bone 2(3%) and liver 1(1.6%) patients. Second malignancy occurred in 4(6.5%) patients, 2(3%) breast, 1(1.6%) lung and endometrium each. Conclusion: Phyllodes tumour was recurrent in 19% of patients, most commonly metastasising to lungs. Radiation helped in reducing the recurrence.

Keywords: Phylloides Tumour, Radiation, Surgery

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Digital Poster Over-Treatment or Under-Treatment: Where the US Stands with Accelerated Partial Breast Irradiation for Favorable-Risk Ductal Carcinoma in Situ Jose G Bazan 1 , Stephanie Yoon 1 , Yousef Ismael 2 , Peter Wu 3 1 Radiation Oncology, City of Hope, Duarte, USA. 2 Radiation Oncology, University of Iowa, Ottumwa, USA. 3 Radiation Oncology, City of Hope, Arcadia, USA