S310
Clinical - Breast
ESTRO 2026
Digital Poster 3670
Results: The median age was 71 years (range 60–91), and the median follow-up was 24 months (range 11–42). Ninety patients were treated with the UH regimen and eighty-nine with the MH regimen. No statistically significant differences were observed in ARD severity between the two regimens (p = 0.57). However, differences were noted in the timing of ARD onset: in the UH group, ARD predominantly developed about two weeks after treatment completion, whereas in the MH group, onset occurred more frequently around the second week of treatment (p = 0.044) (Figure 1).
Palliative Breast Radiotherapy for Symptomatic Advanced Breast Cancer: A 10-Year Experience from a Regional Center Yoon Young Jo, Ji Woon Yea, Jaehyeon Park, Se An Oh, Jae Won Park Radiation oncology, Yeungnam University Medical Center, Daegu, Korea, Republic of Purpose/Objective: Palliative radiotherapy (RT) to the breast or chest wall is an effective treatment option for symptomatic advanced or metastatic breast cancer, providing rapid symptom relief and potential local control. However, evidence regarding its clinical outcomes and prognostic factors in real-world settings, particularly at regional tertiary referral centers, remains limited. This study aimed to evaluate the efficacy, survival outcomes, and predictors of response following palliative breast RT in symptomatic advanced breast cancer patients. Material/Methods: We retrospectively reviewed 34 patients (38 lesions) who received palliative RT to the breast or chest wall between January 2015 and December 2024 at a single tertiary referral center. Median age was 56.5 years (range, 29–79), and 92% had metastatic disease at the time of RT. Median total dose to GTV was 50 Gy (range, 30–62.5 Gy), corresponding to a median BED to GTV ( α / β =4) of 78.9 Gy. Treatment response, symptom relief, toxicity, and survival were analyzed. Results: After a median follow-up of 9.5 months, the median overall survival (OS) was 12.8 months, and the 1- and 2-year OS rates were 57.6% and 39.9%, respectively. The 1- and 2-year in-field local control (LC) rates were 79.6%. Multivariate analysis identified ≥ 3 prior lines of systemic therapy (HR 42.08, p = 0.013) and ≥ 3 symptomatic lesions (HR 32.71, p = 0.011) as adverse prognostic factors for OS, whereas use of SIB or GTV boost (HR 0.003, p = 0.007) was associated with improved survival. Higher BED to PTV ( α / β =4) significantly correlated with improved LC (HR 0.909, p = 0.019). ER-/HER2- subtype predicted worse PFS (HR 42.48, p = 0.004) and DMFS (HR 20.94, p = 0.001). Symptom relief within 3 months after RT was achieved in 31 of 38 treated lesions (82%) and was associated with improved outcomes across survival endpoints. Grade ≥ 3 acute toxicity occurred in 9% of cases, and no grade ≥ 2 late toxicity was observed. Conclusion: Palliative breast radiotherapy provided durable local control and symptom palliation with acceptable toxicity in patients with symptomatic advanced or metastatic breast cancer. Higher radiation dose (BED ≥ 75 Gy) and use of SIB or GTV boost improved survival
Conclusion: Although ADR severity did not differ significantly between ultra- and moderately hypofractionated regimens, the temporal profile of onset varied. These results highlight the need to tailor follow-up and supportive care based on the fractionation schedule. Specifically, patients treated with UH regimens – where ARD tened to emerge after RT completion - may benefit from intensified post-treatment monitoring to ensure early detection and management of acute skin toxicities. References: 1. Brunt AM, Haviland JS, Wheatley DA, et al. FAST- Forward Trial Management Group. One versus three weeks hypofractionated whole breast radiotherapy for early breast cancer treatment: the FAST-Forward phase III RCT. Health Technol Assess. 2023 Nov;27(25):1-176. 2. Lee SF, Kennedy SKF, et al. Randomised controlled trials on radiation dose fractionation in breast cancer: systematic review and meta-analysis with emphasis on side effects and cosmesis. BMJ. 2024 Sep 11;386:e079089. Keywords: Breast cancer, Acute dermatitis, Onset
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