ESTRO 2024 - Abstract Book

S1499

Clinical - Lower GI

ESTRO 2024

Conclusion:

The current study suggests that ART could be considered a viable alternative to completion TME for high risk patients after local excision of early-stage rectal cancer. Particularly, ART can avoid the possibility of permanent stoma, considering the quality of life (QoL) in lower rectal cancer patients.

Keywords: rectal cancer, local excision

1047

Proffered Paper

CT derived body-composition parameters in radiotherapy response for locally advanced rectal cancer

Ross K McMahon 1 , Ross D Dolan 1 , Sean M O'Cathail 2 , Jonathan J Platt 3 , Michael Digby 3 , Paul G Horgan 1 , Colin W Steele 1 , Campbell SD Roxburgh 1 1 School of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Academic Unit of Surgery, Glasgow, United Kingdom. 2 School of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Wolfson Wohl Cancer Research Centre, Glasgow, United Kingdom. 3 Glasgow Royal Infirmary, Radiology / Imaging Department, Glasgow, United Kingdom

Purpose/Objective:

The standard management of Locally advanced rectal cancer (LARC) includes neoadjuvant radiotherapy +/- chemotherapy (NAT) prior to resection (1-3). Pathological Complete Response (pCR), with no evidence of tumour after resection, or Clinical Complete Response (cCR) after NAT have similar 5-year disease-free survival rates >90% (4, 5). There is an unpredictable spectrum of NAT response, with no reliable biomarkers (6). Host characteristics, including measurements of the systemic inflammation response (SIR) and body composition parameters (BCp), have garnered interest as consistent prognostic tools in colorectal cancer (7). Computerised Tomography (CT) derived measurements of fat and muscle parameters have enabled thresholds for visceral fat (VF), subcutaneous fat (SF), and skeletal muscle to be defined. This allows for reproducible analysis of BCp within cancer (8-12). The role of BCp as potentially modifiable indicators of NAT response remains relatively unexplored. Here we explore the relationship of BCp as predictors of response to NAT. We also aimed to determine how BCp relate to circulating markers of SIR – as reflections of the host circulating environment. A secondary aim was to determine if the body-composition significantly changed between staging and re-staging scan intervals after NAT.

Material/Methods: