Associations of volumetric whole-body 18F-FDG PET/CT parameters with the CA 19-9 level and haemogram parameters in pancreatic adenocarcinoma.

Abstract

The present study compared metabolic and volumetric fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) parameters [metabolic tumour volume (MTV), total lesion glycolysis (TLG), and maximum standardized uptake value (SUVmax)] with carbohydrate antigen (CA) 19-9 tumour marker levels and haemogram parameters [(neutrophil-lymphocyte ratio, mean platelet volume (MPV), and platelet-lymphocyte ratio] as prognostic and diagnostic markers of pancreatic cancer. A total of 66 patients who underwent 18F-FDG PET/CT in our nuclear medicine clinic between February 2017 and March 2019, and had a diagnosis of pancreatic adenocarcinoma, were included in this retrospective study. The enrolled patients had not been administered steroids or operated on. Among these patients, whose haemogram parameters and tumour markers could not be assessed by PET/CT within the same week were excluded. The MTV, TLG, and SUVmax values were calculated from primary tumours and metastases in all patients. Spearman's rho correlation, used to examine the relationship between the CA 19-9 level and PET parameters, revealed a statistically significant positive correlation of CA 19-9 with the whole-body MTV (MTVWB) (P<0.001) and whole-body TLG (TLGWB) (P<0.001). Although no significant relationship was found between the neutrophil count and TLGWB according to Spearman's rho correlation, in an artificial neural network using the hidden layer activation function, the neutrophil count showed the strongest association with MTVWB among all included variables. The primary pancreatic tumour MTV and TLG values showed statistically significant positive correlations with the metastases MTV, metastases TLG, MTVWB, and TLGWB values. The CA 19-9 level is considered an important marker of tumour load; it shows a statistically significant positive correlation with parameters such as MTVWB and TLGWB, which provide a measure of the whole-body tumour load. It appears that the MTV and TLG values of the primary pancreatic tumour could also be used as markers of the whole-body tumour load, given their associations with MTVWB and TLGWB.