ESTRO 2024 - Abstract Book

S1561

Clinical - Lower GI

ESTRO 2024

Keywords: deep regional hyperthermia, thermal dose

2897

Poster Discussion

The Systemic Inflammatory Reponses predicts radiotherapy response in locally advanced rectal cancer

Ross K McMahon 1 , Sean M O'Cathail 2 , Hari Nair 1 , Colin W Steele 1 , Jonathan J Platt 3 , Michael Digby 3 , Paul G Horgan 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 treatment for locally advanced rectal cancer (LARC) is neoadjuvant radiotherapy +/- chemotherapy (NAT) prior to surgery (1). The extent of NAT response is an important prognosticator. Pathological complete responders (pCR) represent the epitome of good response (2). When a patient has achieved a clinical complete response (cCR) after NAT, they can be entered into an active surveillance pathway (3). A spectrum of NAT response exists, with a dearth of reliable response predictors. The host response to treatment remains unexplored (4, 5). Within operable colorectal cancer, haematological markers of elevated systemic inflammatory response (SIR) are associated with poor overall survival (6, 7). Studies have suggested that an elevated SIR pre-NAT, including C-reactive protein (CRP), The modified Glasgow Prognostic Score (mGPS) and Neutrophil/Lymphocyte Ratio (NLR), are associated with poorer response to NAT in LARC (8, 9). Similarly, raised carcinoembryonic antigen (CEA) levels have demonstrated potential for use as prognosticators to response (10).

The current study aimed to comprehensively evaluate haematological markers of SIR pre- and post-NAT, as well as the significance of percentage changes to these markers.

Material/Methods:

We included consecutive LARC patients from a single health board if they underwent curative-intent NAT between start dates; June 2016 – July 2021. Pre-NAT blood tests were defined as the preceding sample taken closest to and within 60 days of NAT start. Post-NAT blood tests were taken at a time point following completion of NAT, prior to surgery.

Results: