ESTRO 2020 Abstract Book

S579 ESTRO 2020

patients). A reduced or poor contraction or inhibition of the pubo-rectal muscle in DRE performed within 2 years was reported in the 73% whereas it resulted of 45% in DRE performed after 2 years (8 patients for each group). Regarding functional assessment, incontinence at rest was showed in 5 (45%) and 7 (39%) patients, at DRE performed within or after 2 years, respectively. Globally, MSKCC score seemed to overestimate functional assessments in 5 (17%) patients. Table 1 reported DRE characteristics and the MSKCC score for each patient.

modulated radiotherapy (SIB-IMRT) (220 cGy/die, total dose 5500 cGy). We administered: 5-fluoracil and leucovorin or capecitabine, alone or in association with cisplatin (Plafur) or oxaliplatin (Capeox). In patients enrolled in an Italian trial, oxaliplatin was associated to raltitrexed (Tomox). Four groups of patients were identified: fluoropirimidine chemotherapy plus 50 Gy (Fluoropirimidine group), Plafur chemotherapy plus 50 Gy (Plafur group), Tomox-Capox chemotherapy plus 50 Gy (Tomox-Capox group) and capecitabine with a dose escalation up to 55 Gy (Dose intensification group). pCR was evaluated according to Mandard tumor regression grade (TRG). The Kaplan-Meier method was used to estimate OS, DFS and LC. Results Of the 322 patients analyzed, 80.8% had cT3 tumors and 303 (94.1%) underwent surgery. Table 1 reported the percentage of patients in each sub-group and the number of patients performing sphincter-saving surgery. The primary endpoint was tumor regression grade rate: TRG1 was obtained in 81 (26.7%) patients, TGR2 in 46 (15.1%), TRG3 in 100 (33.0%), TRG4 in 69 (22.8%) and TRG5 in 5 (1.7%) patients. Data were missing for 2 patients (0.7%). The major pathological response (TRG1-2) rate was 41.8%. The proportion of patients with a TRG 1-2 was higher in the Dose intensification group compared to the Fluoropirimidine, Plafur and Tomox-Capeox group, with a statistical significance difference in the dose intensification group (p= 0.046) (Table 1). The 5- and 10- year OS, DFS and LC rates were 82.5%±2.5% and 65.5%±3.8%, 81.2%±2.4% and 79.3%±2.9%, 93.1%±1.7% and 90.5%±2.1%, respectively. The different rates of 5- and 10- year OS, DFS and LC for patients with TRG1-2 and TRG3-5 and the outcomes for the different sub-groups were reported in Table 2.

Conclusion Despite the small number of analysed patients, sphincter dysfunctions rate in our patients treated with a dose intensification schedule was in line with literature. DRE resulted to be a valid tool to evaluate anorectal function, giving information regarding both sphincter morphology and functionality. DRE is advantageous to evaluate incontinence during Valsalva, completing a qualitative evaluation of the MSKCC score. Both DRE and MSKCC could be considered for an accurate sphincter evaluation. PO-1094 Pathological complete response and outcomes in rectal cancer patients with treatment intensification C. Rosa 1 , M. Di Tommaso 1 , L. Caravatta 1 , M. Taraborrelli 1 , D. Fasciolo 1 , A. Augurio 1 , R. Cianci 2 , M. Di Nicola 3 , D. Genovesi 1 1 Ospedale Clinicizzato S.S. Annunziata, Radiotherapy Oncology- Chieti, Chieti, Italy ; 2 Ospedale Clinicizzato S.S. Annunziata, Department of Radiology, Chieti, Italy ; 3 G. D’Annunzio University, Laboratory of Biostatistics- Department of Medical- Oral and Biotechnological Sciences, Chieti, Italy Purpose or Objective Preoperative long-course chemoradiotherapy (CRT) followed by total mesorectal excision (TME) is a standard of care for locally advanced rectal cancer (LARC) patients, aiming to reduce locoregional recurrences and increase pathological complete response (pCR). To improve clinical outcomes, we retrospectively evaluated pCR, disease free survival (DFS), overall survival (OS) and loco-regional control (LC) rates in patients with treatment intensification strategies, according to the different CRT schedules used as dose escalation and/or drug combination. Material and Methods We analyzed 322 LARC patients (M: 209; W: 113). RT was performed by 3D conformal technique, with a total dose of 4500 cGy (180 cGy/die) followed by a sequential boost of 540 cGy (180 cGy/die; total dose 5040 cGy), or a concomitant boost of 1000 cGy (100 cGy/die, 2 times/week; total dose 5500 cGy) with a 3D-CRT technique or with a simultaneous integrated boost with intensity

Conclusion Neoadjuvant CRT in LARC patients resulted in favorable long-term oncologic outcomes with high pCR rate (TRG1- 2: 41.8%). Dose intensification strategy seems to obtain a major pathological response higher respect to drugs combination. PO-1095 Does CEA decrease after radical treatment of unresectable rectal cancer predicts the outcome? M. Kraszkiewicz 1 , A. Napieralska 1 , L. Miszczyk 1 , W. Majewski 1 1 Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Radiotherapy Department, Gliwice, Poland