S707
Clinical – Lower GI
ESTRO 2026
Berlin, Germany. 5 Department of Radiation Oncology, University Hospital Würzburg, Julius-Maximilians- University Würzburg, Würzburg, Germany. 6 Department of Radiation Oncology and Radiotherapy, DiaCura & Klinikum Coburg, Coburg, Germany. 7 Department of Radiation Therapy, University of Leipzig, Leipzig, Germany. 8 Department of Radiation Oncology, Cyberknife and Radiation Therapy, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany. 9 Department of Radiation Oncology, University Hospital Tübingen, Eberhard Karls University Tübingen, Tübingen, Germany, Tuebingen, Germany Purpose/Objective: TNT for locally advanced rectal cancer can improve survival rates and enable an organ-preservation approach for selected patients who achieve clinical complete remission(cCR). However, TNT is associated with more toxicity than CRT, so the benefits must be weighed against the risk of overtreatment. In this study, we analysed the impact of age and sex on oncological outcomes and QoL in patients treated within the CAO/ARO/AIO-12 and CAO/ARO/AIO-16 trials. Material/Methods: Patients were recruited for the CAO/ARO/AIO- 12/CAO/ARO/AIO-16 trials between 2015 and 2020. We analysed the trial data retrospectively to determine the impact of age (stratified <50years, 50-69years and ≥ 70years) and sex. A longitudinal regression analysis was performed, adjusting for baseline clinical/tumor parameters, domain-specific scoring and whether organ preservation was intended, to assess the impact of age and sex on long-term QoL. We analysed the difference in QoL between randomisation and during/after TNT to evaluate the immediate impact of TNT on QoL. Cox regression models were used to analyse oncological outcomes. Results: Of 404, 396 patients were eligible for this analysis. Of these, 130(33%) were female; 56(14%) were under 50 years old; and 83(21%) were 70 years or older. There were no significant differences in oncological outcomes between the sexes, whereas young and older patients had a higher rate of local recurrence (10%/9% vs 3%). The incidence of combined pCR and cCR was slightly lower in younger patients, while they were less likely to undergo extirpation. The cCR/pCR ratio was 0.22 in female and 0.47 in male patients. During and after TNT, the QoL total score based on the EORTC-QLQ-C30 questionnaire deteriorated more often clinically meaningful in female and younger patients.During follow-up, a longitudinal analysis indicated that hair loss and faecal incontinence worsened more in women. Physical functioning and impotence worsened more often in older patients,
Conclusion: This exploratory analysis indicates that variation in vaginal and bulboclitoris dose may relate to specific late vaginal and sexual symptoms after AC RT. While preliminary, these findings highlight the potential importance of detailed female-organ delineation and systematic dose-volume reporting in this setting. Validation in the full DACG-I cohort is needed to determine the robustness and clinical significance of these initial signals. References: 1. Arzola A et al. Daily Vaginal Dilator Use During Radiation for Women With Squamous Cell Carcinoma of the Anus: Vaginal Wall Dosimetry and Patient- Reported Sexual Function. Pract Radiat Oncol 20242. Rooney MK et al. Long-Term Patient-Reported Dyspareunia After Definitive Chemoradiation for Anal Cancer: Using the Anterior Vaginal Wall as an Organ- at-Risk to Define an Actionable Dosimetric Goal. Adv Radiat Oncol 20243. Son CH et al. Dosimetric Predictors of Radiation-Induced Vaginal Stenosis After Pelvic Radiation Therapy for Rectal and Anal Cancer. Int J Radiat Oncol Biol Phys 20154. Kronborg CJS et al. Defining and sparing sexual function-related organs at risk for rectal cancer radiotherapy. Acta Oncol 2025 Keywords: anal cancer, female sexual health, dosimetry The impact of age and sex on quality of life and oncological outcomes in patients with locally advanced rectal cancer undergoing TNT Markus Diefenhardt 1 , Ralf-Dieter Hofheinz 2 , Michael Ghadimi 3 , Claus Rödel 1 , Daniel Zips 4 , Bülant Polat 5 , Gerhard Grabenbauer 6 , Thomas Kuhnt 7 , Emmanouil Fokas 8 , Cihan Gani 9 1 Department of Radiotherapy, Goethe-University Frankfurt, University Hospital, Frankfurt, Germany. 2 Department of Hematology and Oncology, University Medical Center Mannheim, Mannheim, Germany. 3 Department of General, Visceral and Pediatric Surgery, University Göttingen, University Hospital, Göttingen, Germany. 4 Department of Radiation Oncology, Charité-Universitätsmedizin Berlin, Freie Universität Berlin, and Humboldt-Universität Berlin, Mini-Oral 2309
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