ESTRO 2024 - Abstract Book

S459

Clinical - Breast

ESTRO 2024

Patients with moderate to severe fibrosis (group 2) score worse on cosmetic outcome and report lower QoL on psychosocial, physical well-being, satisfaction with breasts and adverse effects of radiation domains than patients in group 1. This emphasizes the importance of reducing the risk of the development of fibrosis. In this preliminary study few patients were treated with reduction mammoplasty, therefore no conclusions can be drawn for this group yet. We are currently expanding the cohort and anticipate further increase of this group, and hypothesize an increase mainly in group 2. The majority of patients that received volume replacement techniques were in group 1. Research into extrinsic risk factors for fibrosis of the breast after BCT, especially in the light of these oncoplastic surgery techniques, is currently ongoing in the STARLINGS study.

Keywords: Fibrosis, cosmetic outcome

247

Digital Poster

Salvage of locally recurrent breast cancer using 45 Gy twice-daily partial breast re-irradiation

Boris A Mueller, Diana Roth O'Brien, Atif Khan, Michael Bernstein, Beryl McCormick, David Guttmann, John Cuaron, Simon Powell, Lior Z Braunstein

MSKCC, Radiation Oncology, New York, USA

Purpose/Objective:

Locally-recurrent breast cancer following breast-conserving therapy (BCT) has historically necessitated mastectomy. To identify alternatives to mastectomy, RTOG 1014 studied the feasibility of repeat BCT using a novel radiotherapeutic (RT) regimen (i.e., 45 Gy delivered in 30 fractions of 1.5 Gy twice-daily to the partial breast, "rePBI"). Having employed this approach since its initial development, we present real-world outcomes of rePBI as salvage therapy.

Material/Methods:

We identified all patients at our institution who underwent repeat BCT and received rePBI for recurrent breast cancer from 2011 to 2019. Clinicopathologic and treatment parameters for the initial primary breast cancer and the subsequent recurrences were documented, and we report rates of recurrence and treatment-associated toxicities.

Results:

The cohort included 34 patients with a median age of 66 (46-78) at the time of rePBI. At a median follow-up of 61.3 months, there were three subsequent locoregional breast recurrences (5-year local control rate 91.2%). One patient developed a regional lymph node recurrence (2.9%), and three developed distant metastases (8.8%). There was no grade ≥ 3 toxicity. The most common acute toxicity (< 3 months) was radiation dermatitis (100%), and common