2961 - Hypofractionated Whole-Breast Irradiation with Concomitant Boost following Breast Conservation Surgery in Early-Stage Breast Cancer
Presenter(s)
P. Kumar1, J. E. Schoenhals1, A. Crum1, S. J. Daniel1, M. Mestres-Villanueva1, Y. Gokun2, T. Pathmarajah3, T. Y. Andraos1, R. Young1, J. M. Eckstein1, T. Jitwatcharakomol1,4, J. R. White5, J. G. Bazan Jr6, E. Healy7, S. R. Jhawar1, and S. Beyer1; 1Department of Radiation Oncology, The Ohio State University Wexner Medical Center, Columbus, OH, 2Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University Wexner Medical Center, Columbus, OH, 3The Ohio State University College of Medicine, Columbus, OH, 4Division of Radiation Oncology, Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, 5Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS, 6Department of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, 7Department of Radiation Oncology, University of California - Irvine, Orange, CA
Purpose/Objective(s): Hypofractionated radiation therapy (HFRT) for breast cancer has shown comparable local control and toxicity to conventional fractionation (CF) whole breast irradiation (WBI). Tumor bed boost improves local control and can be delivered sequentially or concomitantly (CB) with WBI. Initial results from NRG RTOG 1005, with treatment delivered in supine position, reported HFRT with CB over 15 fractions (F) was non-inferior to sequential boost after HFRT or CF WBI in terms of local control, adverse events (AEs), and cosmesis, with the added benefit of reduced treatment time. We report outcomes of HFRT with CB in patients with invasive breast cancer (IBC) and ductal carcinoma in situ (DCIS) with majority treated in the prone position at our institution.
Materials/Methods: We retrospectively identified patients with early-stage, clinically node-negative IBC and DCIS treated with HFRT WBI with CB to the lumpectomy cavity from 2017-2024. All underwent breast-conserving surgery followed by WBI 40 Gy, plus CB to lumpectomy cavity of 48 Gy, delivered in 15 F over 3 weeks using 3D conformal (3DCRT) or intensity modulated radiation therapy (IMRT). Patient demographics, clinical characteristics, and treatment details were collected from electronic medical records. acute and late radiation-related AEs, and cosmesis outcomes were recorded. Radiation AEs were graded with CTCAE v4 and physician-reported cosmetic outcomes were grouped into excellent/good vs. fair/poor per NRG-RTOG Global Cosmetic Score.
Results: 52 IBC and 48 DCIS patients met the inclusion criteria. Median age was 60 years (Interquartile range 51-69), and median follow-up was 18.5 months. Higher-risk features included age <50 years (17%), ER negative (36%), T2 tumor (14%), positive margins (5%), and grade 3 (57%). Majority (94%) of patients were treated in prone position. 3DCRT was used for 99% patients. 31% received chemotherapy, while 55% had endocrine therapy. Most common acute AEs were Grade 1 radiation dermatitis (42%), grade 1 fatigue (57%), and grade 1 breast pain (32%). Most common late AEs were Grade 1 skin hyperpigmentation (17%) and grade 1 induration (13%). No patients developed grade =3 toxicity. Baseline cosmesis, when assessed, was reported as excellent/good in 33 (94%) patients and fair in 2 (6%) patients. At 1 year, 42 (98%) patients had excellent/good cosmesis, and 1 (2%) had fair outcomes. At 3 years, 11 (92%) patients had excellent/good and 1 (8%) had fair cosmesis. No poor cosmetic outcomes were reported.
Conclusion: Combination of HFRT with CB for early-stage IBC and DCIS resulted in low rates of toxicity and favorable cosmetic outcomes. This study reports real-world experience from a single institution using HFRT with a CB to the lumpectomy cavity, delivered in the prone position, for early-stage breast cancer. Longer follow-up with a larger cohort of patients is warranted to better assess clinical outcomes with this treatment approach.