ESTRO 2025 - Abstract Book

S550

Clinical - Breast

ESTRO 2025

Conclusion: Significant pain reduction was observed in patients concurrently treated with CDK4/6 inhibitors and RT, particularly in conventional RT settings and in opioid users, with evidence of limited toxicity. No effectiveness or safety differences were found across subgroups, including the elderly.

Keywords: CDK4/6 , pain, bone metastases

2924

Digital Poster Are there high-risk subgroups for isolated locoregional failure in patients early-stage BC and received mastectomy without adjuvant radiation therapy? Giuseppe Facondo 1 , Chiara Reverberi 1 , Agnese Prisco 1 , Tino Ceschia 1 , Serena Bertozzi 2 , Luca Seriau 2 , Carla Cedolini 2 , Marco Trovo 1 1 Department of Radiation Oncolog, ASUFC "Santa Maria della Misericordia", Udine, Italy. 2 Department of Surgery, ASUFC "Santa Maria della Misericordia", Udine, Italy Purpose/Objective: to determine whether there exist a significant independent association between prognostic factors and loco regional recurrence in early-stage breast cancer (BC) patients treated with mastectomy and adjuvant systemic therapy without post-mastectomy radiation therapy (PMRT). Material/Methods: 343 patients treated between December 2009 and December 2018 were retrospectively reviewed. Tumors were classified by intrinsic molecular subtype and prognostic factors. The Kaplan-Meier method was used to estimate outcomes. Univariate analysis for prognostic factors was performed with the long-rank test and Cox proportional hazards regression was used to estimate hazard ratios (HR) to evaluate the association between factors and survival. Factors with a p-value ≤ 0.10 in the univariate analyses were included in the multivariate analysis (MVA). P values less than 0,05 were deemed statistical significance. Results: Median age at mastectomy was 58 years (IQR 49-74) and median follow-up was 94.1 months (IQR 72-126.9). Median Ki67 was 20% (IQR 10-35; dst 21.63). 126 (36.7%) patients were T2,124 (36.1%) were pN1, 93 (27.1%) grade 3, 66 (19.2%) presented lymphovascular invasion (LVI), 68 (19.8%) were Her2 positive and 31 (9%) were triple negative (TN). 129 patients (37,6%) underwent systemic therapy with chemotherapy. Only 11 (3.2%) patients had a local recurrence, corresponding to a Local Control (LC) at 5 and 8 years of 98.8% and 97.9%, respectively. Five and eight years LC for patients with LVI were 94.8% and 90.6% compared to 99.2% and 98.7% for patients without LVI. Five