S687
Clinical – Lower GI
ESTRO 2026
outcomes assessment in clinical trials with the definition of optimal timepoints and stratification of QoL results across subgroups is necessary. References: 1. Bascoul- Mollevi C, et al. Eur J Cancer.2023;186:151- 1652. Dijkstra ES, et a. Radiother Oncol. 2022; 171:69- 763. Ma H, et al. Int J Radiat Oncol Biol Phys. 2025; 122(1):43-514. Winiarek M, et al. J Clin Oncol.2025; 43(Suppl 4):84-88 Keywords: Total Neoadjuvant Therapy, Quality of Life Digital Poster 783 A underestimated complication? Sacral fractures following radiotherapy for rectal cancer Victoria Alonso Gonzalez 1 , Diego Piedrafita Suárez 2 , Guillermo Veiguela Prado 2 , Johanna Peña Vivas 1 , Alfonso Villacé Gallego 2 , Zahara Martín Rodríguez 2 , Arantzazu Iglesias Aguera 1 1 Radiotherapic Oncology, HUCA, Oviedo, Spain. 2 Medical Physics, HUCA, Oviedo, Spain Purpose/Objective: Pelvic Insufficiency Fractures (PIFs) are recognized, yet often under-reported, as a late complication for pelvic radiotherapy. Although, the connection between PIFs and rectal cancer treatment is unknown. There are limited studies on the incidence and the relation between radiation dose and volume in the literature. This study aims to analyze dose-volume histograms (DVH) to greater understanding of cause and effect relationship. Material/Methods: A sample of 79 patients (45 men, mean age 66.5 years) received concomitant chemoradiotherapy (CRT) for primary rectal cancer (Capecitabin QT: oral, 850 mg·m-2 every 12 hours, 5 days a week for a total of 5 cycles, RT: 50.0-59.4 Gy). Patients underwent pelvic protocol MRI after 2 to 5 months of CRT treatment to identifying PIFs. Sacrum structures were retrospectively delineated. Sacrum maximum and mean dose, as well as V45Gy, V30Gy, V20Gy (in volume percentage) were collected and assessed. These data were analyzed through Fisher’s exact and c2 tests to verify correlations and fittings, respectively. Results: PIFs were present in only 5 patients, which represents 6.3% of the total. This result shows no significant statistical differences with general incidence of fractures, considered to be around 3.5% (p-value = 0.17) according to the literature [1]. However, when patients’ gender was acknowledged as a variable, the results displayed that only women suffered this complication with a ratio of 14.7% (obtaining a p-value of 0.0012 relative to gender’s relevance, through Fisher Exact test). This fact, compared to the values
tolerability (Table 1). Colorectal-specific EORTC QLQ- CR29 analyses confirmed comparable long-term outcomes in bowel- and urinary-related functions, except for dyspareunia, which was worse in the standard CRT arm [MD 7.45 (3.27,11.63); p = 0.0005] (Table 2). Long-term follow-up from the Polish-II study further reinforced these findings, showing equivalent QoL and functional outcomes across FACT-C, QLQ-C30, and physical, family, and emotional domains.
Conclusion: TNT appears to achieve its oncologic benefits without major deterioration in global health status, functional domains, or symptom burden compared with standard CRT. This supports TNT as a patient-centred treatment approach in locally advanced rectal cancer care. Further efforts in standardizing patient reported
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