Usefulness of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography for predicting the prognosis and treatment response of neoadjuvant therapy for pancreatic ductal adenocarcinoma

Abstract

Background: The Response Evaluation Criteria in Solid Tumors (RECIST) for computed tomography (CT) is preoperatively used to evaluate therapeutic effects. However, it does not reflect the pathological treatment response (PTR) of pancreatic ductal adenocarcinoma (PDAC). The Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) for positron emission tomography (PET)/CT is effective in other cancers. This study aimed to confirm the usefulness of PERCIST and the prognostic utility of PET/CT for PDAC.

Methods: Forty-two consecutive patients with PDAC who underwent neoadjuvant therapy (NAT) and pancreatectomy at our institution between 2014 and 2018 were retrospectively analyzed. We evaluated the treatment response and prognostic significance of PET/CT parameters and other clinicopathological factors.

Results: Twenty-two patients who underwent PET/CT both before and after NAT with the same protocol were included. RECIST revealed stable disease and partial response in 20 and 2 cases, respectively. PERCIST revealed stable metabolic disease, partial metabolic response, and complete metabolic response in 8, 9, and 5 cases, respectively. The PTR was G3, G2, and G1 in 8, 12, and 2 cases, respectively. For comparing the concordance rates between PTR and each parameter, PERCIST (72.7% [16/22]) was significantly superior to RECIST (36.4% [8/22]) (P = .017). The area under the curve survival values of PET/CT parameters were 0.777 for metabolic tumor volume (MTV), 0.500 for maximum standardized uptake value, 0.554 for peak standardized uptake value corrected for lean body mass, and 0.634 for total lesion glycolysis. A 50% cut-off value for the MTV reduction rate yielded the largest difference in survival between responders and nonresponders. On multivariate analysis, MTV reduction rates < 50% were independent predictors for relapse-free survival (hazard ratio [HR], 3.92; P = .044) and overall survival (HR, 14.08; P = .023).

Conclusions: PERCIST was more accurate in determining NAT's therapeutic effects for PDAC than RECIST. MTV reduction rates were independent prognostic factors for PDAC.

Keywords: MTV; PERCIST; PET/CT; pancreatic ductal adenocarcinoma.

Figure 1

Representative FDG PET/CT examination before and after neoadjuvant therapy (NAT) revealed a significant decrease in FDG uptake in the tumor (arrow)

Figure 2

Waterfall plot analysis for the reduction rate of each parameter: tumor size, maximum standardized uptake value (SUVmax), and peak standardized uptake value corrected for lean body mass (SULpeak)

Figure 3

Analysis of receiver operating characteristic (ROC) curves to determine the best indicator for predicting the pathological treatment responders. The area under the ROC curve (AUC) values for the reduction rate of tumor size, maximum standardized uptake value (SUVmax), peak standardized uptake value corrected for lean body mass (SULpeak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were 0.478, 0.723, 0.786, 0.576, and 0.661, respectively

Figure 4

Analysis of receiver operating characteristic (ROC) curve to determine the best indicator for predicting recurrence (A) and prognosis (B). For recurrence, the area under the ROC curve (AUC) values for the reduction rate of tumor size, maximum standardized uptake value (SUVmax), peak standardized uptake value corrected for lean body mass (SULpeak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were 0.678, 0.463, 0.558, 0.793, and 0.669, respectively. For survival, the AUC values for reduction rate of tumor size, SUVmax, SULpeak, MTV, and TLG were 0.643, 0.500, 0.554, 0.777, and 0.634, respectively

Figure 5

Survival curve using the Kaplan‐Meier method. A, The relapse‐free survival curve of patients with the metabolic tumor volume (MTV) reduction rate with a 50% cut‐off value. B, Overall survival curve of patients with the MTV reduction rate with a 50% cut‐off value