The relationship between 18F-FDG-PETCT-derived markers of tumour metabolism and systemic inflammation in patients with recurrent disease following surgery for colorectal cancer

Aim: 18F FDG-PETCT derived markers of tumour metabolism have been reported to have prognostic significance in a variety of tumours. Host inflammation is also recognised to have prognostic significance. The aim of the present study was to investigate the relationship between these markers and host systemic inflammation in patients undergoing elective surgery for colorectal cancer. Methods: Patients with histologically confirmed colorectal cancer, who underwent elective surgery between 2008 and 2015, who also underwent 18F FDG-PETCT, at a single centre were included (n =103). Neutrophil lymphocyte ratio (NLR) and modified Glasgow Prognostic Score (mGPS) were derived from routine blood tests. The maximum standardised uptake (SUVmax), peak standardised uptake (SUVpeak), metabolic tumour volume (MTV) and total lesion glycolysis (TLG) were measured. Results: There was no association between 18F FDG-PETCT measures of tumour metabolism and systemic inflammation in the 33 patients who underwent preoperative imaging. Of the 70 patients with recurrent disease who underwent 18F FDG-PETCT during follow up, patients with NLR ≥5 had a significantly higher SUVmax (20 vs 7, p=0.002), SUVpeak (14 vs 5, p<0.001), MTV (29g vs 2g, p=0.001) and TLG (338g vs 9g, p<0.001). Similarly, patients with an mGPS of 1-2 at the time of 18F FDG-PETCT had a significantly higher median SUVmax (11 vs 6, p=0.048), SUVpeak (8 vs 4, p=0.046), MTV (13mL vs 2mL, p=0.005) and TLG (146g vs 10g, p=0.004). Conclusions: The present study reports a direct association between 18F FDG-PETCT derived measures of tumour metabolism and systemic inflammation in patients with recurrent colorectal cancer.