ESTRO 38 Abstract book

S786 ESTRO 38

simultaneous integrated boost and capecitabine chemotherapy for distal rectal cancer. Material and Methods A total of 26 patients with locally advanced distal rectal cancer were enrolled from March 2015 to May 2016. The tumor had to have evidence of cT3-T4 with any N, or any T with N1 or N2 disease on pelvic magnetic resonance imaging (MRI), staged according to the 2009 classification of the American Joint Committee on Cancer (7th edition). The radiation dose fractionation was 58.75 Gy/25 fractions (2.35 Gy/fraction) for rectal tumor and pelvic lymph node metastasis and 50 Gy/25 fractions for pelvic lymph node stations, accompanied with simultaneous capecitabine chemotherapy. Completion of the simultaneous chemotherapy was ensued by 1 week of rest and then another cycle of induction chemotherapy with capecitabine. A radical rectal cancer surgery was performed 6-8 weeks after the simultaneous chemoradiotherapy. The primary endpoints were the complete pathological response rate and the postoperative sphincter preservation rate. This study was a non-randomized, open-labeled, single-arm, single- institution, prospective, phase II trial. All patients provided written informed consent before they were recruited for the study.

EP-1449 Prognostic Value of Volumetric PET Parameters in Patients with Locally Advanced Rectal Cancer F. Sert 1 , A. Oral 2 , R. Savas 3 , D. Yalman 1 , S. Ozkok 1 1 Ege University Medical School&Hospital, Radiation Oncology, Izmir, Turkey ; 2 Ege University Medical School&Hospital, Nucleer Medicine, Izmir, Turkey ; 3 Ege University Medical School&Hospital, Radiology, Izmir, Turkey Purpose or Objective For locally advanced rectal cancer (LARC) patients, preoperative neoadjuvant radiochemotherapy followed by total mesorectal excision (TME) is the standard treatment. The aim of our study is to determine the prognostic and/or predictive role of 18F-FDG PET/CT parameters such as SUVmax, SUVmean, Metabolic Tumor Volume (MTV) and Total Lesion Glycolysis (TLG=MTVxSUVmean) for the patients with LARC treated with neoadjuvant radiotherapy±chemotherapy(nCRT).

Results All 26 patients completed the neoadjuvant chemoradiotherapy, among which 25 received surgical treatment, and 1 patient declined the surgery due to severe perianal edema. The postoperative complete pathological response rate was as high as 32% (8/25), while the sphincter preservation rate was 60% (15/25); the overall T/N downstaging rate was 92% (23/25), and the R0 resection rate was 100%. During the chemoradiation, the occurrence rate of grade 1 adverse reactions was 85% (22/26), including 10 hematologic toxicities, 11 cases of diarrhea, 12 cases of excretory response, 9 cases of radiodermatitis, and 5 cases of hand-foot syndrome; the occurrence rate of grade 2 acute adverse reactions was 53.8% (14/26), including 7 cases of hematologic responses, 8 cases of diarrhea, and 2 cases of radiodermatitis. There were 2 cases of grade 3 acute adverse reactions, both of which were radiodermatitis. None of the acute adverse reactions were more severe than grade 4. After the surgery, there was one case of ureteral injury and one case of intestinal obstruction, but no perioperative deaths occurred. Conclusion In conclusion, the chemoradiation regimen of preoperative VMAT-SIB 58.75Gy and a single cycle of induction chemotherapy with capecitabine for patients with distal rectal cancer is safe and feasible with a satisfactory complete pathological response rate, sphincter preservation rate, and R0 resection rate.

Material and Methods Between January 2005 and December 2016, a total of 106 patients with clinical T3-4 and/or N+ rectal cancer without distant metastasis were included this retrospective evaluation. Totally 106 patients met our criteria. Median age was 61 (range, 29-86) and 54% of them were female. Patient characteristics are shown in table 1. Correlation between metabolic and volumetric parameters and tumor characteristics was evaluated. Prognostic factors for overall survival (OS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) were analyzed. All patients were treated with concurrent chemotherapy except 18 (17%) of them. Among the patients receiving concurrent chemotherapy 68 (64%) received oral capecitabine, and 20 (19%) received 5- Fluorouracil with leucovorin during RT. Results The median follow-up duration for all patients and surviving patients was 39.0 months (range, 6–103 months) and 40 months (range, 22–103 months), respectively. Sixteen patients (15%) developed distant metastases, and