ESTRO 36 Abstract Book

S676 ESTRO 36 2017 _______________________________________________________________________________________________

Target volume coverage and homogeneity were comparable between the different planning techniques. We compared multiple dose volume parameters to OAR including V40 Gy and V50 Gy to the bowel cavity, V45 Gy to the bladder, mean dose to femoral heads using IMRT, 2 arc VMAT and 3 arc VMAT techniques and found no significant differences in any parameter. Both 3- and 4- field proton treatment plans demonstrated significant sparing on V40 Gy to the bowel cavity: median volume using 2 Arc VMAT was 667 cc, 3- and 4-field proton therapy 522 cc and 535 cc respectively. V45 Gy to the bladder was also considerably lower using protons: 2 arc VMAT 49,3% vs. 23,4% and 28,5% using 3- and 4-field proton therapy. Mean dose to femoral heads was significantly lower with proton therapy while V40 Gy and V30 Gy to the sacral bone were comparable. Conclusion We found dosimetric equality on the selected parameters for OAR when comparing 2 arc VMAT with fixed field IMRT and 3 arc VMAT, and no differences between 2 and 3 arc VMAT either. VMAT reduces overall treatment time and is a feasible option for standard treatment planning in SCCA. In four patients with high V40 Gy to the bowel proton treatment plans proved superior in V40 Gy to the bowel, V45 Gy to the bladder, and mean dose to femoral heads with the potential to reduce subsequent toxicity. Data on acute toxicity will be presented at the meeting. S.H. YOUN 1 , D.Y. KIM 1 , T.H. KIM 1 , S.Y. KIM 2 , J.H. BAEK 2 , Y.J. CHA 2 , H.J. CHANG 2 , M.J. KIM 2 , S.C. PARK 2 , J.H. OH 2 1 National Cancer Center, Proton Therapy Center, Goyang-si-, Korea Republic of 2 National Cancer Center, Center for Colorectal Cancer, Goyang-si-, Korea Republic of Purpose or Objective To investigate clinical outcome of non-metastatic rectal cancer patients with extremely high pretreatment serum CEA level after radical surgery following preoperative chemoradiotherapy Material and Methods A total of 959 patients with clinical stage II-III rectal cancer who underwent preoperative chemoradiotherapy followed by radical surgery between October 2001 and July 2011 were retrospectively analyzed. There were 332 patients with elevated pretreatment serum CEA level (> 5ng/ml) and among them, we defined 23 patients with CEA level of > 50 ng/ml as an extremely high pretreatment CEA group. Overall survival rate, relapse-free survival rate, locoregional recurrence-free survival rate and distant metastasis-free survival rate were compared between pretreatment CEA levels of 5-50 ng/ml and > 50 ng/ml. Results Median follow-up duration was 69 months (range, 3-165). The five-year survival rate were 80.5% and 73.4%, and the 10-year survival rate were 64.5% and 73.4% in patients with pretreatment serum CEA level of 5-50 ng/ml and > 50 ng/ml, respectively ( p = 0.672). The extremely high CEA group (> 50 ng/ml) had significantly lower relapse-free survival rate (RFS) at 5-year and 10-year than patients with CEA level of 5-50 ng/ml (5-year RFS 70.6% versus. 52.2%, and 10-year RFS 62.1% versus. 52.2%, p = 0.048, respectively). Also, patients with extremely high CEA (> 50ng/ml) had trend to lower distant metastasis-free survival rate (DMFS) (5-year DMFS 72.0% versus. 55.9%, and 10-year DMFS 67.4% versus. 55.9%, p = 0.087, respectively), and there were no differences in locoregional recurrence-free survival rate (LRRFS) (5-year LRRFS 89.3% versus. 81.8%, 10-year LRRFS 82.8% versus. 81.8%, p = 0.355). Conclusion This study showed that non-metastatic rectal cancer patients with extremely high pretreatment serum CEA EP-1270 Clinical outcome of non-metastatic rectal cancer patients with extremely high CEA level

level (> 50 ng/ml) had higher risk of relapse with trend of increasing distant metastasis. EP-1271 Is 3D-CRT still a valid option in radical radiochemotherapy of anal carcinoma in the era of IMRT? S. Shakir 1 , A. Garant 2 , S. Alshehri 2 , D. Slobodan 3 , T. Alcindor 4 , T. Vuong 1 1 Jewish General Hospital, Radiation Oncology, Montreal, Canada 2 McGIll University Health Center, Radiation Oncology, Montreal, Canada 3 Jewish General Hospital, Medical physics, Montreal, Canada 4 McGIll University Health Center, Medical oncology, Montreal, Canada Purpose or Objective Intensity Modulated Radiation Therapy (IMRT) is well accepted in our institution as standard radiation technique for patients with anal canal cancer. We are reporting treatment related toxicity profiles recorded during treatment with 3D conformal radiation (3D-CRT) versus IMRT with radical concomitant radiochemotherapy at McGill University Health Center. Material and Methods This is a retrospective study of all patients’ charts diagnosed with squamous cell carcinoma of anal cancer from January 2002 to May 2009. The standard treatment was radical radiation with 2 cycles of chemotherapy using 5-Fluorouracil (1000mg/ m 2 daily for 4 days in a 24 hours continuous perfusion) and Mitomycin-C (at 10 mg / m 2 ). Radiation doses were 50.4 Gy, 54 Gy and 60 Gy in 28, 30, 33 fractions to macroscopic disease for T1, T2/T3, and T4 tumors respectively and 30 Gy in 15 fractions to microscopic nodal disease at risks. Demographic data, treatment modality, different acute toxicities and tolerance as well as outcomes were compared between patients treated with 3D-CRT using conformal diamond diagonal opposing fields [1], and those treated with IMRT. Results From January 2002 to May 2009, 90 patients (3D-CRT: 40, IMRT: 50) treated with radical intent were included in this study. The median age for the entire cohort was 57 years. Male to female ratio was 0.61. Fifty-four percent (n=41) of patients had greater than stage II disease (table 1-A). Acute toxicities were collected prospectively with weekly blood tests, intra treatment weekly evaluation for bowel frequency, skin-reaction and hospital admission for treatment related toxicity. Toxicity grading was based on the national cancer Institute common toxicity criteria version 2.0. The rates of ≥ grade 2 skin, hematological and gastrointestinal toxicities for 3D-CRT group were 65%, 45% and 25% respectively; whereas for IMRT group; 58%, 48% and 20% respectively with corresponding p values of 0.522, 0.834 and 0.617 respectively. Treatment interruption rate was significantly higher (p value: 0.018) with 5% vs 24% rate among patients treated by 3D-CRT vs IMRT, despite a non-significant difference for higher grade 3 hematological rate of 20% versus 28% for 3D-CRT and IMRT groups, respectively, (p = 0.46), (table 1-B). Conclusion Acute toxicity profiles did not differ significantly between the two radiotherapy techniques, but treatment interruption was significantly higher in IMRT group with a trend of higher grade 3 hematotoxicity. Thus, 3D-CRT diamond fields remain a valid option for patients with anal canal cancer. Since May 2009, IMRT has become our standard treatment and we are now looking at its impact on local control in our patient population.