ESTRO 2024 - Abstract Book

S1530

Clinical - Lower GI

ESTRO 2024

Patients were eligible for protocol inclusion if they were >18 years old, had a performance status of 0-1, biopsy proven diagnosed of distal/middle locally advanced rectal adenocarcinoma, stage cT3-cT4 and/or cN1-cN2. Patients received short-course radiotherapy (5×5 Gy) followed by six cycles of XELOX chemotherapy (capecitabine 1000 mg/m2/12h on days 1-14, oxaliplatin 130 mg/m2 on day 1). Patients with clinical complete response (cCR) after completing TNT were offered "Watch & Wait (W&W)" therapy vs. surgery. The primary endpoint was clinical complete response (cCR) and pathological complete response (pCR) in both patients undergoing W&W or surgery. Secondary endpoints included overall survival, local control, distant metastasis, and toxicity profile. Between December 2020 and June 2023, 35 patients were recruited according to the inclusion criteria.

Results:

Out of 35 patients, 24 (68%) achieved a good/complete clinical response after TNT. 13 of them (55%) underwent W&W therapy with satisfactory results in oncological controls. 11 of them (45%) underwent surgery, with complete pathological response in the surgical piece. 11 (32%) of 35 patients obtained poor/moderated clinical response, in which cases surgery was performed with a radiology-pathology (rad-path) correlation of 100%. The most common G1-G2 adverse events were neurological toxicity (41%), fatigue (32%), diarrhoea (19%), and rectal pain (8%). G3 adverse events (neurological toxicity and fatigue) occurred in 3 (9%) of 35 patients. There were no cases of local recurrence or distant metastasis during the follow-up period. Treatment-related death occurred in one patient due to an infectious complication.

Conclusion:

Short-course radiotherapy plus preoperative chemotherapy followed by surgery/W&W is an efficacious with acceptable toxicity alternative for locally advanced rectal cancer, which offers advantages compared to the standard treatment. Nonetheless, future large-scale prospective studies are required to evaluate these treatment results.

Keywords: TNT, Short-course, Neo-adjuvant.

1916

Mini-Oral

Quality of life and toxicity in patients with pancreatic adenocarcinoma treated on a 1.5T MR-Linac

Jasmijn M. Westerhoff 1 , Jacobien C.M. Scheepens 1 , Martijn P.W. Intven 1 , Uffe Bernchou 2,3 , Beth Erickson 4 , Helena M. Verkooijen 1 , John P. Christodouleas 5 , Gert J. Meijer 1 , Tine Schytte 2,3 , Lois A. Daamen 1 , William A. Hall 4 1 University Medical Center Utrecht, Department of Radiation Oncology, Utrecht, Netherlands. 2 Odense University Hospital, Department of Oncology, Odense, Denmark. 3 University of Southern Denmark, Department of Clinical Research, Odense, Denmark. 4 Medical College of Wisconsin, Department of Radiation Oncology, Milwaukee, USA. 5 Elekta, Elekta, Stockholm, Sweden

Purpose/Objective: