ESTRO 2020 Abstract book

S398 ESTRO 2020

There are nutritional risks in most cervical cancer patients receiving radiotherapy, and the linoleic acid metabolic pathway is closely related to occurences of radiation enteritis. The upregulation of linoleic acid pathway indicates the increased nutritional risks. PD-0655 Comprehensive analysis of patient outcome after local relapse of locally advanced cervical cancer M. Fabien 1 , A. Schernberg 1 , S. Gouy 2 , A. Maulard 2 , L. Alexandra 2 , C. Genestie 2 , A. Pierre 1 , M. Kissel 1 , I. Fumagalli 1 , P. Pautier 3 , E. Deutsch 1 , C. Haie-Meder 1 , P. Morice 2 , C. Chargari 1 1 Institut Gustave Roussy, Département de radiothérapie, Villejuif, France ; 2 Institut Gustave Roussy, Département de chirurgie gynécologique, Villejuif, France ; 3 Institut Gustave Roussy, Département d'oncologie médicale - Gynécologie, Villejuif, France Purpose or Objective The dose escalation allowed by image-guided adaptive brachytherapy (IGABT) has resulted in a major increase in local control rates in locally advanced cervical cancer patients. Local relapses have become a rare event, reflecting a highly radio-resistant disease with poor prognosis. Only scarce data are available on the outcome of patients experiencing a local relapse after IGABT. Feasibility of salvage treatments is uncertain. Material and Methods Between 2004 and 2016, all consecutive patients treated at our Institute for locally advanced cervical cancer and receiving concomitant chemoradiation (CRT) and IGABT were analysed for treatments (including dosimetric data), patterns of local relapse, symptoms related to local progression, treatments of relapse, and survival data. Clinical and treatment-related prognostic factors for survival after local relapse were searched, in order to potentially identify patients requiring aggressive salvage treatment. Results Two hundred and fifty-nine patients were treated during this period. With a median follow-up of 4.1 years, 10.8% (n = 28) had a local relapse with a median onset time of 8 months after brachytherapy completion. Among these patients, 53.6% had synchronous lymph nodes or distant metastatic relapse and only 13 patients (5% of all patients) had isolated local relapse. After local relapse, median survival was 47 months and only three patients (10.7% of the patients with relapse) were alive at last follow-up. Only three patients with local relapse could receive salvage surgery (10.7%). Metastases occurrence and pelvic wall involvement were the main contra-indications (67.9%) for salvage surgery. Among the three patients treated with surgery, two are still alive at last follow-up without significant complication. Improved survival was observed among the two patients who could have surgery (p=0.02). Local progression led to serious symptoms in 75% of patients. There was no significant difference in survival between patients with only local relapse and those with synchronous distant failure. Only the time interval between brachytherapy and relapse (<1 year) was prognostic for 2-year overall survival (p=0.005). Conclusion Salvage surgery is feasible in a very low number of highly selected patients with local relapse following IGABT. Local failure is a major cause of severe local symptoms, confirming that every effort should be done to achieve long-term local control through dose escalation, even in patients at high risk for distant failure.

PD-0656 A contouring atlas on MRI of emerging pelvic female organs at risk for daily practice radiotherapy A. Allajbej 1 , F. Patani 1 , L. Gasparini 1 , F.C. Di Guglielmo 1 , C. Bonfiglio 1 , D. Fasciolo 1 , C. Rosa 1 , M. Trignani 1 , A. Vinciguerra 1 , L. Caravatta 1 , M. Di Tommaso 1 , R. Cianci 2 , R. Basilico 2 , A. Augurio 1 , D. Genovesi 1 1 SS.Annunziata, Radiation oncology, Chieti, Italy ; 2 SS.Annunziata, Radiology, Chieti, Italy Purpose or Objective Pelvic Radiotherapy (RT) is widely used for neoadjuvant, adjuvant or definitive treatment. Improvement of new RT techniques requires accurate definition of organs at risk (OARs). Magnetic Resonance Imaging (MRI), thanks to a better soft tissue definition, provides an optimal delineation of pelvis anatomical structures. The aim of this study was to produce a MRI-based RT atlas for delineation of new and emerging OARs in female pelvic region, considered most relevant for RT practice. Material and Methods After an accurate literature review, the structures of interest were identified. 3Tesla-MRI simulation was performed according to our protocol for pelvic cancer treatments: full bladder and empty rectum. Radiation oncologists jointly with radiologists identified and contoured selected structures visible on T2 sequences (axial, coronal and sagittal planes). Results Emerging identified OARs were (Figure 1): • Internal Anal Sphincter (IAS) is the innermost muscle layer of anal canal, visible as a direct continuation of the circular smooth muscle of rectum, with an intermediate signal intensity.

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External Anal Sphincter (EAS), PuboRectal Muscle (PM), and Levator Ani Muscle (LAM): EAS forms the outer muscle layer of anal canal and it continues cranially with the PRM and LAM, respectively. LAM anchors the sphincter complex to the inner side of the pelvis. All these muscles appear hypointense. Internal Obturator Muscle (IOM) originates from the obturator foramen, surrounded by the ischium and pubic bone and IRF. Ischio-Rectal Fossa (IRF) triangular shaped, isrepresented by fat and connective tissue Bladder Neck (BN) is well represented on sagittal plane as the hypointense funnel-shaped lower portion of the bladder, anterior to the vagina, continuing caudally in the urethra. (LMM) appear hyperintense with the same signal intensity as surrounding soft tissue. Vagina (V) is a hypointense structure with a rumpled lumen that forms an H or W appearance in cross sections, due to apposition of the vaginal walls. Cervix (C) is a circular structure, from the junction of vaginal canal to the uterus, presenting higher signal intensity than vagina The anatomo-radiological boundaries identified to recognize these structures are shown in Table 1. Labia Majora and Minora

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