ESTRO 2021 Abstract Book

S80

ESTRO 2021

Conclusion This is the first study to identify regions where dose relates to reactive FTi using IBDM. Our final model includes both functional subunits involved in tongue motion and the brainstem. The results suggest the development of swallowing dysfunction and malnutrition during treatment may be due to a complex combination of the effects from radiotherapy on local muscular and distant neurophysiological function. Future research will investigate this relationship. [1] doi:10.1117/1.JMI.1.2.024003 [2] doi:10.1016/j.radonc.2018.10.028

Poster highlights: Poster Highlights 4: Lower GI (colon, rectum, anus)

PH-0110 Surgical Tolerability after Chemoradiotherapy. Preliminary Data of phase III OPERA in rectal cancer J. Gerard 1 , N. Barbet 2 , B. Thamphya 3 , A. Dhadda 4 , N. Magné 5 , L. Mineur 6 , M. DEBERNE 7 , T. Zilli 8 , A. Sun Myint 9 1 Centre Antoine Lacassagne, Radiothérapie, Nice, France; 2 Centre Bayard, Radiothérapie, Villeurbanne, France; 3 Centre Antoine Lacassagne, Biostatistique, Nice, France; 4 Yorkshire hospitals, clinical oncology, HULL, United Kingdom; 5 Institut de cancérologie Loire, radiothérapie, Saint Priest en Jarest, France; 6 Institut Sainte Catherine, radiothérapie, Avignon, France; 7 CHU Lyon Sud, radiothérapie, Pierre Bénite, France; 8 Hopital Universitaire Genève, radiothérapie, Genève, Switzerland; 9 Cancer center Clatterbridge - Liverpool, radiothérapie, Liverpool, United Kingdom Purpose or Objective Organ preservation (OP) for rectal cancer is gaining popularity. The OPERA trial (NCT02505750) aims to test the hypothesis that a Contact X Ray brachytherapy (CXB) boost can increase the rate of OP compared to External beam Radiotherapy boost. We report the preliminary blinded surgical tolerability following high dose used with CXB. Materials and Methods OPERA is a European phase 3 trial. Inclusion criteria: any age > 18y, PS 0-1 operable patient, adenocarcinoma T2-T3 a/b < 5cm ᴓ , N0-1, distal, middle rectum. Stratification made between tumor diameter