ESTRO 38 Abstract book

S799 ESTRO 38

improvement in OS in patients treated with TMT (TMT: 83.7% vs. CRT: 57.3%; p=0.052). (Figure 2a,b) The median time to death was 5.1 years (range: 0.9 to 15.7 years) in the TMT group and 4.1 years (range: 0.8 to 18.2 years) in the CRT group. Conclusion Despite prior reporting, ACC continues to be a therapeutic dilemma for gastrointestinal oncologists. This retrospective cohort suggests a benefit of TMT over non- operative management for ACC although CRT may be considered a reasonable alternative for patients favouring functional organ preservation. The role of adjuvant chemotherapy remains to be elucidated. EP-1474 Preoperative RT-CT in locally advanced rectal cancer using different RT doses; our experience D. Delishaj 1 , I.C. Fumagalli 1 , A. Cocchi 1 , A. Vola 1 , G. De Nobili 1 , F. Gherardi 1 , F. Bonsignore 2 , F. Tagliabue 3 , J. Arnoffi 4 , R. D'Amico 1 , F. Declich 2 , A. Ardizzoia 4 , C.P. Soatti 1 1 Ospedale Manzoni di Lecco, Department of Radiotherapy, Lecco, Italy ; 2 Ospedale Manzoni di Lecco, Department of Medical Physics, Lecco, Italy ; 3 Ospedale Manzoni di Lecco, Department of Surgery, Lecco, Italy ; 4 Ospedale Manzoni di Lecco, Department of Clinical Oncology, Lecco, Italy Purpose or Objective Colorectal cancer (RC) is the most common gastrointestinal (GI) malignancy. More than half patients (pts) affected by RC consist in LARC and preoperative RT- CT followed by total mesorectal excision (TME) is the standard treatment in these pts.. The aim of this study was to evaluate pathological response and toxicities in pts affected by LARC underwent neoadjuvant RT-CT using From January 2014 to September 2018 we analyzed 33 pts affected by LARC treated with neoadjuvant RT-CT followed by surgery. Fifteen pts were female (45,5 %) and 18 pts were male (55,5 %). The median age was 68 years old with a range wide from 36 to 80 years old. Twenty-two pts (Group 1) received 55 Gy in 28 FF (45 Gy to the pelvis and 55 Gy to the T, N+ and mesorectum in SIB technique) + Capecitabine 1650 mg/mq/day; 11 pts (Group 2) received 50.4 Gy to the pelvis in 28 FF + Capecitabina 1650 mg/mq/day. We evaluated clinicopathological characteristics of Tumour (T), Nodal (N), grading, margins, N-down-staging, T-down-staging, toumor regression and sphincter preservation. According to CTCAE vs 5 scale acute and late toxicity was evaluated. Results After a median follow-up of 38 months (range 3-48 months) the PFS at 2 and 4 years was 93,2% and 82,%, respectively. At histological examination 5 pts (15,2 %) had a T- complete response (CR), 21 pts (63.6%) had N-CR and 4 pts (12.2%) had both T and N-CR. There was no statistically differences between two groups (p-value > 0,05). Tumour down-staging was observed in 23 (66,6%) pts (68 % Group 1 and 63.5 % Group 2; p-value 0,78). Nodal down-staging was reached in 90 % of pts (100 % in Group 1 and 77 % in Group 2; with a trend in favor of Group 1, p- value= 0,082). Four pts had disease progression (2 pts in Group 1 and 2 in Group 2). Of them 3 pts distant metastases and one pt had locally and distant metastases. All pts underwent systemic treatment. Overall sphincter preserving was reached in 79,9 % (90v% Group 1 and 65 % Group 2; p-value 0,012). Finally, GI and GU G2/3 acute toxicity was observed in 6 pts (18,2 %): 3/22 (13,6 %) Group 1 and 3/11 (27,2%) Group 2. Conclusion Neoadjuvant RT-CT with SIB technique and TD of 55 Gy/28ff (45 Gy to the pelvis and 55 Gy to mesorectum, T and N+) showed an advantage regarding N-down-staging and sphincter preserving compared to standard RT treatment (50.4 Gy/28ff). Acute and late toxicity was two different doses. Material and Methods

presence of opportunistic pathogens such as Fusobacterium nucleatum , which in turn could be responsible, at least in part, of the higher levels of inflammation found in these patients. These data point out the importance that gut microbiota could have in the appearance and develpment of CRC-associated to obesity and could give new clues for the development of new diagnostic tools for CRC prevention. EP-1473 Anal adenocarcinoma: a comprehensive review of management practices and clinical outcomes J. Lukovic 1 , J. Kim 1 , A. Liu 2 , J. Ringash 1 , J. Brierley 1 , R. Wong 1 , A. Barry 1 , L. Dawson 1 , B.J. Cummings 1 , M. Krzyzanowska 3 , E.X. Chen 3 , D. Hedley 3 , R. Prince 3 , F. Quereshy 4 , A. Easson 4 , C.J. Swallow 5 , R. Gryfe 5 , E. Kennedy 5 , A. Hosni 1 1 Princess Margaret Cancer Centre - University Health Network- University of Toronto, Department of Radiation Oncology, Toronto, Canada ; 2 Princess Margaret Cancer Centre, Department of Biostatistics, Toronto, Canada ; 3 Princess Margaret Cancer Centre - University Health Network- University of Toronto, Department of Medical Oncology, Toronto, Canada ; 4 University Health Network- University of Toronto, Department of Surgical Oncology, Toronto, Canada ; 5 Princess Margaret Cancer Centre - Mount Sinai Hospital- University of Toronto, Department of Surgical Oncology, Toronto, Canada Purpose or Objective Primary adenocarcinoma of the anal canal (ACC) is rare. There is a lack of consensus regarding the optimal treatment for these patients. The purpose of this retrospective cohort study was to evaluate the multidisciplinary management outcomes of patients with ACC to better define the optimal treatment paradigm. Material and Methods Patients with anal cancers treated at a tertiary cancer center from Jan 1995 to Dec 2016 were identified. Definitive treatment was either chemoradiation (CRT: 52- 63 Gy with concurrent 5-fluorouracil [5FU] and mitomycin- C [MMC]) or trimodality therapy (TMT: abdominoperineal resection [APR] with adjuvant or neoadjuvant CRT [45- 50Gy with concurrent 5FU or capecitabine]). Baseline characteristics were compared between the treatment groups. Local (LF) and regional failure (RF), and distant metastasis (DM) cumulative incidences were estimated. The Kaplan-Meier method was used to estimate progression-free survival (PFS) and overall survival (OS). Cumulative incidence and survival outcomes were compared between two treatment groups using the log rank test. Results There were 1007 cancer patients identified and 89(8.72%) had ACC histology. Eleven (12.4%) had distant metastases, 36(46.2%) were treated with TMT, 23(29.5%) received CRT, 8(8.99%) were treated with wide local excision, 7(7.87%) received palliative care, and 4(4.49%) were treated at outside cancer centers. The 5-year LF was 9.4% in the TMT group vs 50.8% in the CRT group (p=0.003). (Figure 1a) In the TMT group, 3 patients (2/3 had a positive radial margin) failed locally 3, 8, and 22 months after definitive treatment and were treated palliatively. Out of the 23 patients treated with CRT, 7(30.4%) never achieved a complete response and 9(39.1%) experienced LF. The median time to LF was 4.2 years (CRT) and not reached for patients treated with TMT. Eight of the CRT patients had an isolated local recurrence and were treated with salvage APR. The 5-year cumulative incidence of colostomy was 53.6%. There was no difference in the 5-year RF cumulative incidence (TMT: 10.1% vs. CRT: 21.2%; p=0.231) or DM (TMT: 27% vs. CRT: 25.6%; p=0.734). (Figure 1b,c) There was no difference in PFS at 5 years (TMT: 48% vs. CRT: 32.2%; p=0.178) and a borderline significant