ESTRO 2025 - Abstract Book

S79

Invited Speaker

ESTRO 2025

- Finally, the impact of salvage brachytherapy on hormonal therapy modulation will be examined, particularly in delaying ADT initiation and prolonging disease-free intervals in intermittent ADT regimens.

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Speaker Abstracts Breast cancer Cristina Gutiérrez Miguélez 1 , Jean-Michel Hannoun-Levy 2 1 Radiation Oncology, Institut Català d'Oncologia, Barcelona, Spain. 2 Radiation Oncology, Antoine Lacassagne Cancer Centre, University Cote d'Azur, Nice, France

Abstract:

Breast relapses occur in 3-7% of breast cancer patients at 10y. In these cases, the standard treatment is mastectomy.

However, our Breast Group inside GEC-ESTRO have published enough evidence that we can avoid mutilation and perform a second conservative treatment with a second lumpectomy and a re-irradiation around the new surgical bed with multicatheter interstitial brachytherapy. I am going to explain the evidence we have developed in our European Breast Group. In 2013 we published a retrospective series of 217 patients with 4% rate of new local relapse at 5y, and excellent/good cosmesis in 85% of cases. Median follow-up after the IBTR was 3.9 years. Five and 10-year actuarial 2nd LR rates were 5.6% and 7.2%, respectively. Five and 10-year actuarial DM rates were 9.6% and 19.1% respectively. Five and 10-year actuarial OS rates were 88.7% and 76.4%, respectively. In MVA, histological grade was prognostic factor for 2nd LR (p = 0.008) and OS (p = 0.02); while tumor size was prognostic factor for DM (p = 0.03). G3-4 complication rate was 11%. Excellent/good cosmetic result was achieved in 85%. In 2021 our group published a Propensity Score-Matched Cohort analysis, 377 patients treated with salvage mastectomy compared with 377 with second conservative treatment including Brachytherapy. The characteristics of both groups were very similar. In the matched analyses, no differences in 5-year overall survival and cumulative incidence of third breast event were noted between mastectomy and conservative treatment (88% vs 87%, P = .6 and 2.3% vs 2.8%, P = .4, respectively). Similarly, no differences were observed for all secondary endpoints: DFS, metastasis nor OS. Five-year incidence of mastectomy 3.1% (95% CI, 1.0-5.1). The only significant unfavorable factor was the interval between primary and salvage surgery < 36 months. In 2023 we published our results on 508 patients with salvage surgery and reirradiation with BQT, a retrospective multicenter study, and we created the term “GEC-ESTRO TAM score”, a score to predict the possibility of a new relapse (3rd event) considering APBI and molecular classification, and the interval between primary and salvage surgery. Main outcome was 5-year cumulative incidence (CI) rate of second local relapse. All analyzed patients were classified according to risk groups for Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) accelerated partial breast irradiation (APBI) and molecular classification and time interval between first and second breast surgery (TIS1S2). Finally, we combined GEC-ESTRO APBI, molecular, and TIS1S2 risk groups, leading to the definition of a new score (named TAM: score based on the combination of time interval [T] between first and second surgery and APBI [A] and molecular [M] classifications) specifically designed for 2nd IBTE oncological outcome analysis. From July 1994 to January 202, 508 patients received a 2nd CT. At the time of 2nd IBTE, median age was 64.6 years (range, 56.2-72.6). With a median follow-up of 60.9 months, the 5-year second local relapse CI rate was 4%. The 5-year distant metastasis disease CI rate was 7%. Five-year disease free and overall survival rates were 89% and 91%, respectively. In multivariate analysis, TAM score was an independent prognostic factor for all the oncological items (P < .001) except disease-specific survival (P = .07) and