281 - An Update of a Phase II Trial of Ultra-hypofractioNated Adjuvant Radiotherapy ± sImultaneous Integrated Boost for Low-Risk Breast Cancer (UNIQUE)
Presenter(s)
H. Jing1, X. Nie2, Y. Zhang3, Y. Song1, K. Men3, and S. Wang1; 1State Key Laboratory of Molecular Oncology and Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 2Department of Radiation Oncology, Qingdao Central Hospital, Qingdao, Shandong, China, 3Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
Purpose/Objective(s): Integration of simultaneous boost (SIB) into 5F_WBRT ultra-hypofractionation has not been validated thoroughly. Here we present the result with a full recruitment and longer FU for a phase II prospective study, to evaluate the feasibility of 5F_WBRT±SIB in early-stage pts (NCT05762900).
Materials/Methods: Eligibility: invasive or non-invasive breast cancer, definitive surgery with R0 margin and axillary nodal evaluation and pT1-2N0-1M0. A daily 5.2Gy for 5f WBRT ± SIB of 6Gy/f to the tumor bed was applied. Dose constraints: heart Dmean<3Gy, V7<5%, V1.5<30% and brachial plexus Dmax<27.5Gy and V27<3cc. Modern techniques such as VMAT was permitted. The primary end point: =G2 breast acute adverse events (AE) and =G3 lymphopenia within 12w after RT (CTCAE 4.0). According to the Simon’s two-stage design, in the initial 67 pts, only 7 (10.8%) developed the AE. Then we went on recruiting for >200 pts to rule out a 5yr incidence of any =G2 late AE >30%.
Results: From 2022.7 to 2025.2, 266 pts were recruited, with details present at the meeting. The RT course was 7d (5-10). Four pts (1.5%) reported acute breast swelling and under coverage of the PTV.
In all, 232 (87.2%) pts were monitored for =12w with full evaluation of acute AE, among whom 25(10.8%) had G2 breast AE (no G3 AE), including 4(1.7%) breast pain, 15(6.5%) breast edema and 6(2.6%) itching. Four (1.7%) pts had G3 lymphopenia (LPE). The mFU time was 15.0ms (0.3-30.9), none has any sign of relapse. In the 195 (73.3%) pts who were monitored for =6 ms, 24(12.3%) reported chronic breast edema (19(9.7%) G1 and 5(2.6%) G2); 22(11.3%) had breast shrinkage (14(7.2%) G1 and 8(4.1%) G2) and 77(39.5%) had induration (67(34.4%) G1 and 10 (5.1%) G2). Rib fractures were detected by CT scans in 12(6.2%) at 13ms (11.5-15) post RT, most (66.7%) were asymptomatic. None reported symptomatic heart, lung or neurological AE or G3 late AE. In the 251 pts (94.4%) who received BCS, 246(98%) had breast evaluations. And 213(86.6%), 25(10.2%) and 8(3.3%) reported excellent, good and moderate cosmesis at the last FU. In all, in 255 pts who had any blood tests from the initiation to 6ms post RT, 123 (48.2%) had LPE, with 84(32.9%) G1, 37(14.5%) G2 and 2(0.8%) G3 LPE.Conclusion: The updated results revealed a general feasibility of 5F WBRT+SIB. In the acute phase, 37 pts (14.0%) had =G2 breast toxicity or =G3 LPE. In the subacute phase, 29 pts (11.1%) had =G2 breast AE by now, with 96.8% reported excellent/good cosmesis. We will continue to monitor the long-term AE and cosmesis before a solid conclusion.
Abstract 281 - Table| G0(%) | G1(%) | G2(%) | |
| Worst breast pain in 12w | 161(61.7) | 95(36.4) | 5(1.9) |
| Pain at the last FU | 235(90.0) | 26(10.0) | 0 |
| Worst breast edema in 12w | 163(62.5) | 82(31.4) | 16(6.1) |
| Edema at the last FU | 231(88.5) | 28(10.7) | 2(0.8) |
| Worst itching in 12w | 211(80.8) | 44(16.9) | 6(2.3) |
| Itching at the last FU | 254(97.3) | 7(2.7) | 0 |
| Worst skin toxicity | 37(14.2) | 224(85.8) | 0 |
| Pigmentation at the last FU | 171(65.5) | 90(34.5) | 0 |
| Shrinkage at the last FU | 199(76.2) | 21(8.0) | 7(2.7) |
| Induration at the last FU | 171(65.5) | 80(30.7) | 10(3.8) |