1003 - Acute and Long-Term Patient-Reported Outcomes (PRO) by Breast-Q(TM) Prospectively Collected after Accelerated Partial Breast Irradiation (APBI) Delivered Once Daily (QD) vs. Alternating Days (QOD) Post Lumpectomy for Early-Stage Breast Cancer
Presenter(s)
S. S. Varghese1, N. W. Johnson2, Y. Cao1, R. C. Chen1, M. G. Boersma3, J. P. Einck1, D. Keleti1, A. Morris1, K. Rhodes-Stark4, C. K. Savioz1, S. R. Stecklein1, A. Tejwani1, and J. R. White5; 1Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS, 2University of Missouri, Kansas City, MO, 3Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS, 4Deaprtment of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS, 5University of Kansas Comprehensive Cancer Center, Kansas City, KS
Purpose/Objective(s): ASTRO Guidelines endorse 30 Gy /5 fractions (F) delivered QOD as one of the preferred APBI external beam fractionation schedules to minimize patient toxicity. Our institution has prospectively collected disease-specific PROs on all patients receiving radiation therapy (RT) since 2022. This study aims to assess patient-reported acute and late breast symptoms resulting from 5-fraction APBI delivered QD vs QOD.
Materials/Methods: We included patients treated with APBI from 1-2022 to 12-2024 who completed PRO surveys at baseline and at least 1 follow-up. Skin toxicity and physical well-being were measured using the Breast-QTM Breast Cancer Core Checklist (“adverse effects of radiation,” and "Physical Well-Being: Chest” forms) Version 2.0, administered at baseline, then 1-, 6-, 12-, and 24-months post RT. For Skin Toxicity, patient bother is scored for six items as 1 -none, 2- a little, 3 - a lot, for a total score from 6 to 18 (lower score = less bother) and was analyzed as a raw score. Per the BREAST-QTM protocol, physical well-being scores the frequency of experiencing 10 breast symptoms in the last week (1-none, 2-sometimes, 3-always) that are totaled and undergo Rasch transformation, ranging from 0 -100 (higher score = better well-being). Between-group comparisons were performed using two-sample t-tests and Mann–Whitney U tests. Minimal important difference (MID) was calculated to be =3 for Rasch-transformed scores based on 0.2 times the SD of the mean Rasch score at baseline and at each time point.
Results: A total of 205 patients were included: 54 in the QD group and 151 in the QOD group. The groups were comparable in age, tumor characteristics, receptor status, Oncotype score, and PTV volume (Table1). QD group had lower PRO skin toxicity scores at all post-RT time points vs QOD group, with significant differences at 1 and 12 months (all p <0.05). Mean Rasch-transformed score for breast physical well-being was significantly higher in the QD group vs QOD group at all points post-RT (all p<0.05). The difference in mean Rasch scores between QD and QOD groups exceeded the calculated MID at all post-RT time points, meeting the threshold for clinical significance. QD showed early improvement in Rasch-transformed scores for breast well-being vs the QOD group, indicating quicker recovery from RT-related breast symptoms.
Conclusion: Patient-reported symptoms using Breast-QTM support less skin toxicity and improved physical well-being of the breast after APBI delivered QD compared to QOD. Recovery from breast symptoms was quicker in the QD group than in the QOD group. Table 1: Patient characteristics| APBI QD (n=54) | APBI QOD (n=151) | |
| Age, years, median (IQR) | 68 (61-73) | 67 (61-75) |
| Dose per fraction, mean± SD, cGy | 573 ± 9.5 | 589.7 ± 14.9 |
| Total Number of fractions | 5 | 5 |
| Total elapsed days, median (range) | 6 (4-8) | 10 (7 -19) |
| Tumor size, mean ± SD (mm) | 11.3 ± 5.9 | 11.5± 9.1 |
| Oncotype score, median | 13 | 15 |
| PTV_lump volume, mean ± SD (cc) | 177 ± 80.4 | 194.7 ± 82.6 |
| Luminal A n (%) | 27 (50) | 62 (41) |
| Luminal B, HER2 Negative n(%) | 27 (50) | 89 (59) |