S2727
RTT - Patient preparation, immobilisation, and verification protocols
ESTRO 2026
Purpose/Objective: Deep inspiration breath-hold radiotherapy (DIBH-RT) is a standard cardiac-sparing technique for left breast cancer. Despite its dosimetric advantage, poor breath- hold reproducibility may undermine target coverage1. An internal 2022 audit found only 23.7% of patients met departmental DIBH eligibility criteria. This single- institution study evaluates the impact of breath-hold home training on spirometry-based DIBH performance. Material/Methods: Between July 2023 and January 2024, 100 left breast cancer patients referred for DIBH-RT were enrolled, with 93 completing the study. Patients received a training package (education booklet, training videos, and nose clip) during initial consultation and were advised to practise at home. Self-administered surveys were given upon signing consent, prior to eligibility session and before CT-Simulation to evaluate anxiety, need-for-information, training compliance, and satisfaction. Anxiety and need-for-information were measured using validated tools: the six-item Spielberger State-Trait Anxiety Inventory short form (STAI-6) and the Amsterdam Preoperative Anxiety and Information Scale (APAIS)2-3. Patients were assessed using institution-specific eligibility criteria by the radiation therapists. Historical audit data from 2022 served as control. Correlations between eligibility, demographics, training compliance, anxiety, and need- for-information were analysed. Results: Patients’ characteristics are summarised in Table 1. Median follow-up from consultation to eligibility session was 13 days (IQR 7.5–20.5). The proportion of patients who met the DIBH eligibility criteria improved significantly from 23.7% (2022) to 51.6% (95% CI of 41%-62.1%, p<.001). Age was negatively correlated with eligibility (rpb=-.325, n=93, p=.001). No significant associations were found with BMI (rpb=-.141, n=93, p=.177), STAI-6 scores ( χ (1)=1.623, p=.444), surgical extent ( χ (1)=2.499, p=.114), smoking history ( χ (1)=.904, p=.342), chemotherapy ( χ (1)=.103, p=.748), DIBH knowledge (rpb=.019, n=93, p=.856), need-for- information (rpb=-.079, n=93, p=.452), home training ( χ (1)=.062, p=.803), training frequency ( χ (1)=.313, p=.958), training booklet usage ( χ (1)=2.272, p=.132), training videos usage ( χ (1)=.176, p=.675), and nose clip usage ( χ (1)=.062, p=.804). Polynomial regression (R ² =0.9953) demonstrated steep eligibility decline between ages 40–50( − 24.8%) and 50–60( − 10.7%), reaching 0% by 67 years (Figure 1). The most frequent reasons for ineligibility were unstable breath-hold (21.5%) and poor breath-hold positional reproducibility (16.1%).
For most patients, immobilisation adhered to the standard protocols. Minor deviations included one UA and one H case in non-neutral positions, and four proximal LL cases with the contralateral leg abducted for better treatment geometry. None required re- imaging or re-planning. Three cases (5.7%) were re- planned and three (5.7%) had suboptimal gantry clearance: One UA case was re-planned due to irreproducibility; two lower arm (LA) cases for insufficient gantry clearance and inadequate stabilisation, respectively. These inadequacies mainly reflected initial implementation challenges with the new protocols. Two proximal LL cases had suboptimal gantry clearance but did not require re-planning.In the control group (46 patients, 48 sites), three cases (6.3%) were re-planned—two with re-imaging—due to suboptimal immobilisation. Protocol adherence in 17 cases (35.4%) would have improved gantry clearance and fluence delivery. Conclusion: Implementing standardised immobilisation reduced re-imaging/re-planning from 6.3% to 5.7% of cases and improved treatment planning with constraints in gantry movement in 5.7% of cases (down from 35.4% of cases). Standardisation also appeared to reduce staff uncertainty and the need for multiple personnel, although this was not formally assessed. Keywords: extremity sarcoma, immobilisation, standardisation Proffered Paper 2674 Impact of breath-hold home training on spirometry-based DIBH eligibility in left breast radiotherapy: results from a single-arm prospective study Muhammad Fairuz Jumee, Li Hoon Lim, Emily Nancy Yu Xuan Caluraud, Eileen Yilin Huang, Harraine Geronimo Soriano, Ju Meng Bryan Ong, Bryan Shihan Ho Division of Radiation Oncology, National Cancer Centre Singapore, Singapore, Singapore
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