ESTRO 2024 - Abstract Book

S496

Clinical - Breast

ESTRO 2024

688

Digital Poster

External Beam Accelerated Partial Breast Irradiation After Second Conserving Surgery

Andrés Muñiz Delgado 1 , Antoni Ramírez 1 , Ángel Infestas 1 , Teresa Montes 2

1 Consorci Sanitari de Terrassa, Radiation Oncology, Manresa, Spain. 2 Fundació Althaia, Surgery, Manresa, Spain

Purpose/Objective:

Accelerated Partial Breast Irradiation (APBI) is a safe technique in early breast cancer after conservative surgery in some cases.

Due to the heterogeneity of both patients and relapses, the best way to re-radiate has not been established. But there are some analyzes of databases or case series with the various techniques with enouhg follow-up. The most used and studied is brachytherapy but also intraoperative.

In this series we analyze if APBI with external radiation therapy achieves the same control while avoiding a mastectomy and the drawbacks of other techniques.

Material/Methods:

A prospective series. 8 patients with previous conservative surgery and radiotherapy with good aesthetic result.

First diagnosis: age 63 (49-84), four Ductal Carcinoma Infiltrating, three In Situ, one Infiltrating Mucinous. Those infiltranting were T1 (3) or T2 (1). Six Luminal, two Triple-Negative. Three adjuvant chemotherapy. Four hormonotherapy five years. 60-66Gy to the bed on 29-33 sessions. Relapse 5-21 years after the first tumor. Age 74 (54-95). Seven cases Ductal Carcinoma Infiltrating, another one Mucinous like before. Five patients Luminal B, one A, one Triple-Negative, another one Her2. Seven T1, one T2; seven N0, one N1 (who underwent lymphadenectomy). Two patients received neoadjuvant chemotherapy, achieving complete response. The rest, pT1, with free margin at surgery. Two adjuvant chemotherapy. Four continue with hormonotherapy. CTV according to diagnosis, surgery and anatomic pathologic. 1.5cm margin of surgical clips, limited by anatomical barriers, and 0.5cm to PTV reaching 84,57cc on average (43.26-155.82cc). Breast: 970.51cc on average (341.59 1.726.99cc). Radiotherapy was planned without breath control. Two or three beams and photons of 6/15MV. 30Gy in 5 non-consecutive-sessions.

Results: