Patient Reported Outcomes Of Early-Stage Breast Cancer Patients After Different Radiotherapy Regimes

De-escalation of radiotherapy (RT) for early stage breast cancer (BC) (in fractionation or volume) is increasingly applied and may improve patient reported outcomes (PROs). We compared PROs of patients treated with different RT regimes. Data was collected from 5 prospective cohorts of BC patients with different RT regimes: intraoperative RT (IORT, 1x23Gy), external beam accelerated partial breast irradiation (EB-APBI, 10x3.85Gy), hypofractionated whole breast irradiation (hypoWBI, 16x2.67Gy), hypoWBI+ boost (hypoWBI-B, 21-26x2.67Gy), and WBI+boost (WBI-B, 28x2.3Gy). PROs of women ≥60 years with invasive/in situ carcinoma ≤30 mm, cN0 and pN0-1a after breast conserving surgery were analyzed with validated EORTC QLQ-C30 and -BR23 questionnaires. Multivariable linear regression analysis with adjustment for confounders (age, comorbidity, pT stage, locoregional treatment, systemic therapy) was used to compare pre-specified PROs of other RT techniques with IORT at 1 and 2 years. To evaluate differences in PROs over time, we used linear mixed models (LMM) including timepoints 3, 6, 12, 24 months after treatment, correcting for confounders. Due to less timepoints, the WBI-B group was excluded in LMM analysis. A p-value of ≤0.01 was significant, while a 10-point difference in PROs score (range 0-100) was deemed clinically relevant. Table 1 shows mean scores per timepoint for Breast Symptoms (BS), Fatigue (FA), Global Health Status (GHS) and Role Functioning (RF). For BS and FA, a higher score is worse, for GHS and RF it is better. One year after treatment, there was no difference in BS between patients treated with EB-APBI and IORT. Patients treated with whole breast irradiation had significantly worse BS compared to the IORT group (all p-values < 0.001). At 2 years the difference persisted only for patients treated with boost. In LMM analysis over time, BS was significantly worse in WBI treated patients. FA, GHS, and RF were significantly worse in the hypoWBI-B group only. In all groups, GHS and RF remained stable over time, FA improved up to 1 year and BS continued to improve up to 2 years after treatment. There were no clinically relevant differences in means between groups at all timepoints, nor significant differences in other PROs. For patients with low-risk BC treated with various radiotherapy regimes breast symptoms continue to slowly improve up to 2 years posttreatment, and they are more common in patients treated with WBI compared to IORT or EB-APBI. However, RT regimen does not substantially influence PROs.Abstract 2056; TableMonthsIORTEB-APBIhypoWBIhypoWBI-BWBI-Bn = 267n = 206n = 375n = 189n = 475Breast Symptoms3 6 12 2415 10 9 816 14 10 921 20 15 1119 19 16 12- - 16 12Fatigue3 6 12 2424 22 20 2025 22 20 2130 26 24 2128 25 19 15- - 19 18Global Health Status3 6 12 2480 79 80 8079 80 81 7975 77 78 8077 77 81 85- - 83 83Role Functioning3 6 12 2486 86 86 8585 85 88 8879 83 84 8679 81 87 90- - 88 88 Open table in a new tab