ESTRO 38 Abstract book

S798 ESTRO 38

clinically and via blood tests before each cycle for toxicity of chemotherapy. All of the patients were able to complete the treatment with no major toxicities (Hand- foot syndrome, hematologic, Skin,Neuropathy and diarrhea) of the chemo observed. Pathologic complete response was seen in 41 (23%) of the patients. R0 resection was observed in 70% of patients. Conclusion Neo-adjuvant chemotherapy CapOx can safely be delivered before chemoradiation and planned surgery.It results in tumor regression, a high rate of delivery of planned therapy, and a substantial pathological CR rate. Chemotherapy is well tolerated in the neoadjuvant settings. Further randomized clinical trials are needed to support this evidence. EP-1472 Obesity and Colorectal Cancer: Impact of the Gut Microbiota J. Gomez-Millan Barrachina 1 , L. Sanchez-Alcoholado 2 , A. Otero 1 , R. Ordoñez 1 , D. Castellano-Castillo 2 , Y. Lupiañez- Perez 1 , M.I. Queipo-Ortuño 2 , A. Román 1 1 Hospital Virgen de la Victoria, Radiation Oncology Department, Malaga, Spain ; 2 Hospital Virgen de la Victoria, Clinical Management Unit of Endocrinology and Nutrition- Laboratory of the Biomedical Research Institute of Málaga IBIMA- Virgen de la Victoria University Hospital- Universidad de Málaga- Málaga- SpainCIBER de Fisiopatol, Purpose or Objective Obesity is considered an important factor in the increased risk of colorectal cancer (CRC) (up to 70%), but the role that the intestinal microbial population plays in this link is not well established. The aim of this study was to determine the intestinal microbiota composition in fecal samples from CRC patients with and without obesity compared to the microbiota present in normal-weight healthy controls, in order to unravel the possible association between gut microbiota, the inflammatory level and the intestinal permeability in the context of The study was conducted over 50 CRC patients (25 patients with BMI<30 km/m 2 and 25 patients with BMI >30 km/m 2 ) who were age and sex paired to 30 normal-weight healthy controls. Fecal bacterial DNA was extracted and analyzed by 16 S rRNA sequencing using an Ion S5 platform and followed by a bioinformatic analysis by QIIME II. Results Patients with CRC had lower bacterial diversity and richness than normal-weight controls, being even lower in CRC subjects with obesity (BMI> 30 kg/m 2 ). The microbiota of CRC patients was characterized by a reduction in butyrate and lactate producing bacteria ( Faecalibacterium prausnitzii , Roseburia , Butyricimonas and Bifidobacterium ) and an increase in opportunistic pathogens ( Streptoccocus , Fusobacterium nucleatum and Escherichia coli ). Moreover, the relative abundance of these opportunistic pathogens was significatively higher in obese CRC patients compared to normal-weight CRC patients and healthy controls. The serum levels of IL-1B (proinflammatory cytokine) and the gut permeability (determined by zonulin levels) were significatively increased in obese CRC patients than in normal-weight CRC patients and healthy controls. Additionally, zonulin levels were significantly correlated with the relative abundance of several microbial groups, being in an positive way with Prevotella in normal-weight CRC patients and with Escherichia coli in obese CRC patients, while negative associations were found with the relative abundance of Ruminococcus and Faecalibacterium prausnitzii in normal-weight controls. Conclusion The presence of obesity in CCR patients is related to lower diversity of microbiota, higher gut permeability, higher obesity-associated CRC. Material and Methods

addressed to watch and wait. The surgical interval was on average 14 weeks after the end of CRT (range 9-21). Total mesorectal excision was performed in 18 pts (with only 1 abdominal-perineal resection). 22.2% of the pts showed pCR, while the CR overall rate (4 pCR+2 cCR) was 30%. As reported in Tab.1, tumor and nodal downstaging was observed in 65% and 95% of pts, respectively.

Conclusion These preliminary results suggest the possibility to treat LARC pts with MRgRT. Although the limited number, the results seem promising if compared to toxicity data available in literature. MRgRT may potentially support PTV margin reduction and dose-escalation in a tailored and personalized treatment perspective. EP-1471 Evaluating the safety and efficacy of neo- adjuvant chemotherapy in locally advanced rectal cancer K. Saeed 1 , T. Sadaf 1 , A.S. Kazmi 1 , S. Butt 1 , A.A. Syed 2 , M.A. Yusuf 3 1 Shaukat Khanum Memorial Cancer Hospital & Research Center., Clinical & Radiation Oncology, Lahore, Pakistan ; 2 Shaukat Khanum Memorial Cancer Hospital & Research Center., Surgical Oncology, Lahore, Pakistan ; 3 Shaukat Khanum Memorial Cancer Hospital & Research Center., Internal Medicine, Lahore, Pakistan Purpose or Objective Standard therapy for locally advanced rectal cancer (LARC) is pre-operative chemo radiotherapy and post- operative chemotherapy. Local recurrence rate for LARC is around 6% while distant recurrence rate is about 25%.Introducing systemic therapy early in the treatment can help control the micrometastasis. Adjuvant chemotherapy is difficult to tolerate due to morbidities of chemoradiation and surgery.We report the safety and efficacy of neo adjuvant chemotherapy before Chemo- radiotherapy on tumor downsizing and pathologic complete response (pCR) in Locally advanced rectal cancer. Material and Methods Records of 244 patients treated between April 2007 to November 2014 were retrospectively reviewed, using the hospital information system. Patients were treated by multi-modality approach. Neo adjuvant Chemotherapy used was 3 weekly cycles of Capecitabine 1000mg/m 2 Day 1-14 per oral and Oxalipatin 130mg/m 2 on Day 1 I/V. Eastern co-operative oncology group (ECOG) performance scale was used to evaluate performance , before chemotherapy.Common terminology criteria for adverse events grades used to measure chemo toxicity. Results 226 out of 244 patients received neoadjuvant chemotherapy.Majority of the patients received 4 cycles before the chemoradiation. Patients were reviewed