ESTRO 37 Abstract book

S788

ESTRO 37

4 San Raffaele Scientific Institute- Milano- Italy, Anatomo Patology, Milano, Italy

Oncologica, Firenze, Italy 2 IFCA, CyberKnife Center, Firenze, Italy

Purpose or Objective To evaluate the impact of robotic stereotactic body radiotherapy (SBRT) with fiducial tracking of liver lesions on clinical benefit rate (CBR), progression free survival (PFS), overall survival (OS) and toxicity in a cohort of oligometastatic colorectal cancer (CRC) patients. To establish if are there any correlations between biologically effective dose (BED), systemic treatment, number of treated lesions, site of primary tumor, presence of extrahepatic disease, number of metastatic lesions and other parameters on the obtained results. Material and Methods Thirty-eight consecutive patients with oligometastatic liver lesions, confirmed by a 18FDG-PET-CT and/or a liver MRI were included, from 2012 to 2017. Patients could have 1-4 liver metastasis and an absent or controlled extrahepatic disease (number of overall metastatic lesions £ 5). For most of the patients, the intended prescription dose was 37,5 Gy in 3 fractions, prescribed to the 70% isodose line to cover 95% of the PTV, and adapted if risk-related. Treatment was delivered with a robotic SBRT, using fiducials tracking. Toxicity was assessed by CTC-AE, scale v. 4.03. Results Between 2012-2017, 38 patients (66 lesions) were irradiated. One patient was excluded from the analysis, for lack of follow-up data. Treatments were delivered every other day (EOD) in a median of three fractions (range 3-5), with a median prescription dose of 37,5 Gy (range 25-45 Gy). The median delivered biological effective maximum dose (maxBED 10 ) was 142 Gy. The CBR was 71,4%, with no significant association with maxBED 10 . After a median follow-up of 11.8 months (range 3.2- 58.8), the 1 and 2-year OS was 67.3% and 44.1%, respectively, with 16 patients (43.2%) dead. Local relapse or distant progression occurred in 28 (77,8%) patients, with a 1 and 2-year PFS of 19.3% and 12.2%, respectively. Age at SBRT > 76 ys and presence of extrahepatic disease had a significant impact on PFS, the last one confirmed at univariate and multivariate analysis; extrahepatic disease and number of metastatic lesions > 3 had a significant impact on OS, both of which significant to univariate analysis. Mean time of local or distant progression was 4,7 months (SD 3.7). No acute grade 3 gastrointestinal (GI) toxicity was found. Conclusion Survival and toxicity results of this retrospective analysis support the importance of the selection of colorectal liver oligometastatic patients that can beneficiate from a stereotactic treatment. More data from prospective clinical trials are needed in order to clarify the role of SBRT as an alternative to surgery. EP-1449 Neoadjuvant chemoradiotherapy IG-IMRT PET based in esophageal or esophageal gastric junction cancer N. Slim 1 , C. Gumina 1 , P. Parise 2 , E. Mazza 3 , A. Cossu 2 , L. Albarello 4 , F. Puccetti 2 , M. Reni 3 , R. Rosati 2 , P. Passoni 1 , N. Di Muzio 1 1 San Raffaele Scientific Institute- Milano- Italy, Radiation Oncology, Milano, Italy 2 San Raffaele Scientific Institute- Milano- Italy, Surgery, Milano, Italy 3 San Raffaele Scientific Institute- Milano- Italy, Clinical Oncology, Milano, Italy

Purpose or Objective to report our experience in patients (pts) with esophageal (EC) or esophageal gastric junction (EGJ) cancer treated

with IG-IMRT PET based. Material and Methods

pts with histologically proven EC or EGJ were submitted to neoadjuvant chemoradiotherapy according to the CROSS study. All pts underwent c-e CT and PET simulation, both repeated for restaging. Radiotherapy (RT) consisted in 41.4 Gy in 23 fractions combined to chemotherapy (ChT) with carboplatin and paclitaxel. Results From April 2014 to November 2016, 40 pts were treated (F: 8; M: 32), median age at diagnosis: 61 years (45-78), median KPS: 90. Twenty- three pts had adenocarcinoma (57.5%), 16 pts had squamous cell carcinoma (40%), 1 pt had adeno-squamous carcinoma (2.5%). Clinical stage was: T2 (11 pts: 27.5%), T3 (27 pts: 67.5%), T4 (2 pts: 5%), N0 (8 pts: 17.5%), N+ (33 pts: 82.5%). The site of tumor was proximal third in 3 pts, middle third in 15 pts, distal - EGJ in 31 pts. Median tumor length was 4.5 cm (1-15). RT was delivered by Tomotherapy in 24 pts and by VMAT in 16 pts. All pts completed RT. Median cycles of ChT was 5 (2-6 cycles), 63% pts received full dose of ChT. The G3 acute haemathological toxicity was: neutropenia in 5 % (2pts), lymphopenia in 70% (28 pts). According to CTCAE vs 3.0, G3 Gastrointestinal toxicity occurred in 12.5% (5 pts). Three pts (7.5%) had bacterial pneumonia, 1 of them died due to complication and one pt had G4 toxicity (massive bleeding from aorto-esofageal fistula) . Responses: 39/40 pts were available (1 pt lost). Median time to restaging was 42 days (14-87). CT/PET showed local RP, SD, RC in 17, 7, 15 pts respectively and PD in 7 pts. Nine pts were excluded from surgery (PD: 5 pts, worsening clinical condition: 2 pts, died: 1pt, lost: 1 pt). Thirty one pts (77.5%) underwent surgery. Median time from CT/RT to surgery was 69 days (15-148). Pt who had massive bleeding from aorto-esophageal fistula underwent urgent surgery 15 days after CT/RT Post-surgery stage was (yp)T0: 3pts (9.7%), T1: 8 pts (25.8%), T2: 8 pts (25.8%), T3: 11 pts (35.4%), T4: 1 pt (3.3%); (yp) N0: 15 pts (48%), N+: 16 pts (52%). 29/ 31 pts (93.5%) had R0. Mandard TRG was: TRG1: 3 pts (10%), TRG2: 5 pts (16%), TRG3: 19 pts (61%), TRG4: 4 pts (13%). Median OS was 15months. 18/31 pts (58.1%) are disease free at a median follow up of 17.4 months (4.1- 42.1), 2 pts had local progression and 11 pts had distant Our data seem to be comparable to those of the CROSS study data in term of R0 and toxicity profile. Differently from CROSS study only 63% of our pts received the full dose of ChT due to the high rate of G3 lymphopenia. This data could explain the lower TRG responses in comparison with CROSS study and the incidence of pneumonia. EP-1450 Elevated tumour markers are related to early treatment failure in oesophageal adenocarcinoma F. Voncken 1 , R.T. Van der Kaaij 2 , J.M. Van Dieren 3 , P. Snaebjornsson 4 , C. Grootscholten 3 , B.M.P. Aleman 1 , J.W. Van Sandick 2 1 Netherlands Cancer Institute- Antoni van Leeuwenhoek, progression. Conclusion