ESTRO 36 Abstract Book

S677 ESTRO 36 _______________________________________________________________________________________________

2015 at 2 academic centres with concurrent chemo- radiation employing either SIB-IMRT or CRT was analysed. The SIB-IMRT group consisted of 87 patients, treated with 2 cycles of Mitomycin and 5-Fluorouracil using a SIB-IMRT based schedule of 42-45 Gy/28-30 fractions to the elective pelvic lymph nodes and 50.4-54 Gy/28-30 fractions to the primary tumor and involved nodes, based on pre- treatment staging. The CRT group comprised 103 patients, treated with Mitomycin or Cisplatin and 5-Fluorouracil or Capecitabine concurrent to CRT with 36 Gy/20 fractions to a single volume including gross tumor, clinical nodes and elective nodal volumes, and a sequential boost to primary tumor and involved nodes of 23.4 Gy/13 fractions. We determined colostomy-free survival (CFS) and overall survival (OS), loco-regional recurrence and distant metastases rates for each radiation modality. Cox proportional-hazards model addressed factors influencing OS and CFS. Propensity score-matched analyses were performed to compare SIB-IMRT and CRT. Results Median follow-up for the entire patient group was 32 months. Average overall treatment time was 42 days in the SIB-IMRT group and 59 days in the CRT group. Patients treated with CRT had significantly higher stage and lower grading. The overall survival at the time of analysis was 74%, similarly for the two groups. Three-year colostomy- free survival was 66% for all patients, with no significant difference between the two groups (61% for SIB-IMRT and 74% for CRT, Log-Rank 0.85). The cumulative incidence of colostomies showed that the majority of events occurred within 18 months in both groups. We found no significant difference in terms of outcomes by univariate analysis and a propensity score analysis adjusted for disparities between the groups.

Fig. 1 Colostomy-free survival Conclusion

Results of this analysis indicate that 3-year clinical outcomes of SIB-IMRT are similar to CRT. Even if highlighting the retrospective observational nature of the study, these data support the routinely use of SIB-IMRT in clinical practice for anal cancer patients submitted to concurrent chemo-radiation. EP-1259 Modern Intensity Modulated Radiotherapy with Daily Image Guidance for Anal Cancer Patients B. De Bari 1 , L. Lestrade 2 , A. Franzetti-Pellanda 3 , M. Biggiogero 3 , M. Kountouri 2 , O. Matziinger 4 , R. Miralbell 2 , J. Bourhis 5 , M. Ozsahin 5 , T. Zilli 2 1 Hôpital Univ. Jean Minjoz, Radiation Oncology, Besançon, France 2 Hopitaux Universitaires de Genève, Radiation Oncology, Genève, Switzerland 3 Clinica Luganese, Radiation Oncology, Lugano, Switzerland 4 Hôpital Riviera-Chablais, Radiation Oncology, Vevey, Switzerland 5 Centre Hospitalier Universitaire Vaudois, Radiation Oncology, Lausanne, Switzerland Purpose or Objective We report the outcomes of the largest populations of anal cancer (AC) patients treated with modern intensity- modulated radiotherapy (IMRT) techniques and daily image guidance. Material and Methods AC patients treated with IMRT +/- chemot herapy in 3 radiotherapy departments were retrospectivel y analysed. They received 36 Gy (1.8 Gy/fraction) on the pelvic and inguinal nodes and on the anal canal, using IMRT (n = 39), volumetric modulated arc therapy (VMAT; n = 15), or helical Tomotherapy (HT; n = 97), and a sequential boost up to a total dose of 59.4 Gy (1.8 Gy/fraction) on the anal and on the nodal gross tumor volumes, delivered with either IMRT (n = 16, until 2011), VMAT (n = 17), HT (n = 61), or 3D-conformal EBRT (CRT, n = 61). Results A total of 151 patients were treated (09/2007 - 03/2015). Of them, 122 presented a stage II - IIIA disease. Chemotherapy was delivered in 138 patients, mainly using mitomycin C and 5-fluorouracil (n = 81). Median follow-up was 38 months (interquartile range, 12-52). Four-year

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Tab. 1 Patient and treatment characteristics and pattern of failure