Main Session
Sep
28
PQA 04 - Breast Cancer, Patient Reported Outcomes/QoL/Survivorship, Functional Radiation Medicine, Hematologic Malignancies, Palliative Care, and International/Global Oncology
2919 - Long-Term Recurrence Outcomes After HDR Brachytherapy Accelerated Partial Breast Irradiation Stratified by Genomic Risk in Early-Stage Breast Cancer
Presenter(s)
John Wilson V, BS - University of South Florida, Tampa, FL
J. D. Wilson V1, J. Redding2, G. Luckey2, R. H. Nanda Jr3,4, K. A. Ahmed3, L. Stout4, P. Blumencranz4, R. Diaz5, and M. N. Mills5; 1Morsani College of Medicine, University of South Florida, Tampa, FL, 2University of South Florida, Morsani College of Medicine, Tampa, FL, 3H. Lee Moffitt Cancer Center and Research Institute, Department of Radiation Oncology, Tampa, FL, 4Morton Plant Hospital, Clearwater, FL, 5Department of Radiation Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL
Purpose/Objective(s):
While recent data suggests partial breast irradiation (PBI) may be safe in high genomic risk patients compared to whole breast irradiation (WBI), outcomes with accelerated PBI (APBI) using HDR brachytherapy stratified by genomic risk remain understudied. We hypothesized that high genomic risk would not be associated with increased ipsilateral breast tumor recurrence (IBTR) after APBI using HDR brachytherapy. The primary objective was to compare the cumulative incidence of IBTR between high- and low-genomic-risk groups in patients treated uniformly with APBI.Materials/Methods:
We analyzed 171 patients with early-stage, ER positive, HER2 negative invasive breast cancer treated from 2010–2022 with lumpectomy, sentinel lymph node biopsy, and APBI using HDR brachytherapy (34 Gy in 10 twice-daily fractions) at one institution who had available genomic testing (Oncotype DX or MammaPrint). High genomic risk was defined as Oncotype DX >25 or high-risk MammaPrint (n=63). Patient, tumor, and treatment characteristics were abstracted from the electronic medical record. Outcomes, including IBTR, regional recurrence (RR), contralateral breast tumor recurrence (CBTR), distant recurrence (DR), any recurrence (AR), and overall survival (OS) were estimated with Kaplan-Meier analysis.Results:
Median follow-up was 88.6 months (range 10.7–189). The median age at the time of PBI was 64 years (range 49-88). Most patients were postmenopausal (n=160). Most tumors were grade 1-2 (N=123) invasive ductal carcinoma (N=152). Adjuvant endocrine therapy was initiated by 161 patients (94%; 58 high-risk, 103 low-risk), and chemotherapy by 41 patients (24%; 39/62 assessable high-risk). There were 18 IBTR events overall (6 in high-risk, 12 in low-risk). Five-year IBTR, RR, CBTR, DR, AR, and OS were 3.8%, 2.0%, 0%, 1.2%, 5.2%, and 4.0%, respectively. High genomic risk patients did not have higher IBTR (5 year 5.2% vs 3.0%, 10 year 10.9% vs 16.9%, p=0.698), RR (5 year 3.9% vs 0%, 10 year 6.6% vs 0.9%, p=0.09), CBTR (5 year 0% vs 0%, 10 year 0% vs 3.3%, p=0.597), DR (5 year 0% vs 1.9%, 10 year 2.7% vs 1.9%, p=0.956), or AR (5 year 7.4% vs 3.9%, 10 year 13.1% vs 19.9 %, p=0.77).Conclusion:
In this large cohort with long-term follow-up treated uniformly with HDR brachytherapy APBI, there were no statistically significant differences in IBTR or other recurrence rates between high- and low-genomic-risk groups. These findings support the oncologic safety of APBI in carefully selected patients with high genomic risk.