2696 - Serial Quality-of-Life Scores Following Ultrahypofractionated Radiotherapy (UHFRT) and Simultaneous Integrated Boost (SIB) Post Breast Conserving Surgery: Largest Real-World Data of a Prospectively Fo

R. Krishnamurthy¹, S. Kenekar², P. Rane³, R. Pathak², S. Joshi⁴, N. Syeda⁵, R. Sarin², and T. Wadasadawala²; ¹Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Homi Bhabha National Institute, Mumbai, India, ²Department of Radiation Oncology, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, India, ³Advanced Centre for Treatment, Research and Education in Cancer, Navi Mumbai, India, ⁴Department of Surgical Oncology, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, India, ⁵Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Navi Mumbai, India

Purpose/Objective(s): We present the most extensive real-world data on quality of life (QoL) changes in breast cancer patients undergoing ultra-hypofractionated radiotherapy (UHFRT) with simultaneous integrated boost (SIB) at a comprehensive cancer center in India. Our study delves into impact of UHFRT with SIB on global and domain-specific QoL, providing crucial insights for the broader implementation of this approach in culturally diverse populations. Materials/

Methods: All patients receiving UHFRT post-BCS, either with Fast-Forward (F-F) or FAST protocols using Forward Planning Intensity Modulated Radiotherapy (F-IMRT) or Inverse Planning Volumetric Modulated Arc Therapy (VMAT) with SIB to tumour bed (TB) using electrons or photons were served EORTC QLQ C30 & BR23 pre-RT (baseline), 1- & 2-years post-RT. Serial median (+/- SD) scale scores were calculated. Patients were grouped domain-wise as QoL stable/better or worse at 1 &2 years vs baseline, with 10 = meaningful difference. Variance across groups was compared using ANOVA or Pearson Chi-Square.

Results: 377 patients (median age 46 +/- 10.5) were accrued (May 2020 - Jan 2022), 60% node-ve, 15% stage III, 26% TNBC, 18% HER2neu +ve. 78.5% received F-F ((26Gy/5#/daily, 32 Gy TB SIB), rest FAST (28.5Gy/5#/weekly, 33Gy TB SIB). 35% received RT to breast + TB, 54% to breast, SCF, TB, rest to IMN also, 39% with VMAT. Mean global health improved from baseline (67 ± 21.5) to 1 yr (74 ± 19.5) & at 2 yrs (80 ± 20). EORTC C30 summary scores increased from baseline (85 ± 15) to 1 yr (92 ± 13) & maintained positive trend at 2 yrs (93 ± 13). 18% reported worse QoL in any 1 domain at 1 yr & 23% at 2 yrs vs baseline. (Table 1) Statistically significant (p = 0.05) correlation noted (not corrected for multiple testing) of worse sexual functioning with older age, postmenopausal status & comorbidities; systemic therapy side effects with chemotherapy & hormone therapy &/or if RT target volume included SCF +/- IMN; cognitive functioning with hormone therapy; fatigue at 1 year with FAST regimen; breast & arm symptoms with postmenopausal status.

Conclusion: Real-world serial QoL data of UHFRT with SIB post-BCS shows notable improvements in global & domain-specific QoL over 2 years, supporting broad adoption of this technique. It is important to monitor QoL with focus on cognitive functioning, sexual functioning, breast & arm symptoms & fatigue, thereby optimizing patient care & outcomes. Table 1: Percent of patients reporting worse QoL scores at 1- and 2-years post RT vs post RT

Scale	% scores worse than baseline
	1 year post RT	2 years post RT
Global health score	15	10
Physical function	16	16
Role function	11	10
Emotional function	13	18
Cognitive function	16	17
Social function	10	9
Fatigue	13	12.5
Nausea/Vomiting	9	6
Pain	14	10
Insomnia	9	8
Dyspnoea	10	9
Constipation	9	5
Diarrhoea	5	6
Appetite loss	6	4
Financial difficulties	13	8
Body image	13	10
Sexual functioning	18	23
Sexual enjoyment	2.9	5
Future perspective	9.5	9
Systemic therapy side effects	10	7
Breast symptoms	18	15
Arm symptoms	18	12.5
Upset by hair loss	1.6	2