Abstract Book

S794

ESTRO 37

and TLV was also assessed. Response to preoperative HCRT was assessed by PET response criteria in solid tumors (PERCIST) and pathological response. Results Clinical complete response rate and pathological complete response rate was 36% and 23%, respectively. Down-staging rate for primary lesions was 60%, and the sphincter preservation rate was 81%. PERCIST, SUVmax after HCRT, and change in SUVmax were significant predictive factors for pathological complete response on univariate analysis. PERCIST was significant predictive factors for pathological complete response on multivariate analysis. Conclusion Preoperative HCRT produced a favorable effect. It was suggested PERCIST was a predictive biomarker of preoperative HCRT response. A. Guido 1 , L. Giaccherini 1,2 , L. Fuccio 3 , S. Fanti 4 , D. Cuicchi 3 , A. Arcelli 1,5 , P. Castellucci 4 , G. Macchia 6 , F. Deodato 6 , S. Cilla 7 , S. Mignogna 8 , V. Picardi 6 , I. Djan 9 , F. Di Fabio 10 , S. Cammelli 1 , A.G. Morganti 1 , V. Valentini 11 1 Radiation Oncology Center, Department of Experimental- Diagnostic and Specialty Medicine – DIMES- University of Bologna- S. Orsola-Malpighi Hospital, Bologna, Italy 2 Radiation Oncology Unit, Department of Oncology and Advanced Technology- Arcispedale S. Maria Nuova, IRCCS of Reggio Emilia, Italy 3 Department of Medical and Surgical Sciences - DIMEC, S. Orsola-Malpighi Hospital- University of Bologna, Bologna, Italy 4 Service of Nuclear Medicine, S.Orsola-Malpighi Hospital- University of Bologna, Bologna, Italy 5 Radiotherapy Department, Ospedale Bellaria, Bologna, Italy 6 Radiotherapy Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II", Campobasso, Italy 7 Medical Physics Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy 8 Medical Oncology Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy 9 Institute of Oncology Vojvodina- Sramska Kamenica, Medical Faculty, University of Novi Sad, Serbia 10 Department of Medical Oncology, S. Orsola-Malpighi Hospital, Bologna, Italy 11 Department of Radiotherapy, Policlinico Universitario “A. Gemelli”- Università Cattolica del Sacro Cuore, Rome, Italy Purpose or Objective To evaluate the pathological response of locally advanced rectal cancer (LARC) after adaptive neoadjuvant intensified radiation therapy (RT) with concomitant and sequential boost Material and Methods Patients with high risk biopsy proven LARC were included. Primary end-point was pathological complete response (pCR). Secondary objectives included acute/late toxicity and predictive value of [18F]FDG-PET/CT. The sample size was calculated on the basis of the two-stage design by Simon. All patients performed [18F]FDG-PET/CT at baseline (PET-0) and after 2 weeks during RT (PET-1). Since now, only 4 patients performed [18F]FDG-PET/CT before surgery (PET-2). IMRT was delivered concurrently with capecitabine-based chemotherapy in all patients. Tumor volume (TV) was delineated using a gradient-based EP-1463 Phase II study of adaptive high-dose neoadjuvant radiotherapy in high risk rectal cancer

Conclusion Systemic immune-inflammation index is strongly associated to clinical results and survival in anal cancer patients submitted to CT-RT. The low cost and the easy profile in terms of determination and reproducibility make SII a promising tool for prognostic assessment in this oncological setting. EP-1462 Prediction of preoperative hyperthermo- chemoradiotherapy response in locally advanced rectal cancer T. Takahashi 1 , H. Murata 2 , H. Shoji 2 , M. Onishi 3 , Y. Takakusaki 3 , N. Okonogi 3 , A. Okazaki 2 , K. Nishimura 1 , T. Yamano 1 , K. Ogoshi 2 , T. Nakano 3 1 Saitama Medical Center- Saitama Medical University, Radiation Oncology, Kawagoe, Japan 2 Hidaka Hospital, Oncology Center, Takasaki, Japan 3 Gunma University- Graduate School of Medicine, Radiation Oncology, Maebashi, Japan Purpose or Objective The aim of this study was to investigate clinical outcomes and predictive biomarker of preoperative hyperthermo- chemoradiotherapy (HCRT) response in patients with locally advanced lower rectal cancer. Material and Methods We performed a retrospective review of 43 patients with stage II-III locally advanced lower rectal cancer who were examined with CT, 18 FDG-PET/ CT and MRI before and after preoperative HCRT. All patients underwent preoperative HCRT followed by total mesorectal excision. Radiotherapy was delivered through IMRT technique. The clinical target volume encompassed the primary tumor and entire mesorectum. Total dose was 40- 50 Gy with daily fraction of 2 Gy. Chemotherapy consisted of capecitabine during radiotherapy. Hyperthermia was performed for once a week for 5 sessions. The standardized uptake value (SUVmax, SUVpeak, and SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLV) of rectal cancer lesions were calculated before HCRT and 6 weeks after preoperative HCRT. In addition to these factors, change in SUV, MTV,