Prognostic value of multiparameter [Ga]Ga-DOTA-FAPI-04 PET/MR imaging biomarkers for patients with advanced pancreatic cancer.

[PURPOSE] In this retrospective study, whether [Ga]Ga-DOTA-FAPI-04 PET/MR imaging biomarkers can predict the progression-free survival (PFS) and overall survival (OS) of patients with advanced pancreatic cancer was investigated.

[METHODS] Fifty-one patients who underwent [Ga]Ga-DOTA-FAPI-04 PET/MR scans before first-line chemotherapy were recruited. Imaging biomarkers, including the maximum tumor diameter, minimum apparent diffusion coefficient (ADC), maximum and mean standardized uptake values (SUV and SUV), fibroblast activation protein- (FAP-) positive tumor volume (FTV and W-FTV) and total lesion FAP expression (TLF and W-TLF), were recorded for primary and whole-body tumors. A subgroup analysis of 28 patients with obstructive inflammation was performed, and the maximum and mean standardized uptake values (D-SUV and D-SUV), FAP-positive uptake volume (D-FTV), and total FAP expression (D-TLF) in the distal pancreas were assessed. Kaplan-Meier analysis and the Cox proportional hazards model were used to assess the relationships between these imaging biomarkers and PFS/OS.

[RESULTS] SUV was negatively correlated with the ADC (r = -0.288, P = 0.041), whereas tumor length was positively correlated with the FTV, TLF, W-FTV, and W-TLF (r = 0.311-0.508, P < 0.05). The median PFS was not reached in patients with a W-TLF ≤ 516.09 but was 91 days in patients with a W-TLF > 516.09 (P < 0.001). Univariate and multivariate Cox regression analyses identified W-TLF as an independent predictor of PFS (P = 0.001, hazard ratio (HR) = 4.949). The TNM stage, tumor length, ADC value, SUV, TLF, W-FTV, and W-TLF were significantly associated with OS (P < 0.05). Multivariate analysis further confirmed that tumor length, ADC, and W-TLF were independent predictors of OS (P < 0.05). A subgroup analysis including 28 patients with obstructive pancreatitis revealed that TNM stage, tumor length, W-FTV, W-TLF, D-FTV, and D-TLF were significantly associated with OS (P < 0.05). The multivariate analysis further identified W-TLF and D-FTV as independent predictors of OS (P < 0.05).

[CONCLUSIONS] [Ga]Ga-DOTA-FAPI-04 PET/MRI biomarkers are associated with the PFS and OS of pancreatic cancer patients. Both the ADC and W-TLF are independent risk factors for patients with advanced disease. Increased fibroblast activity, driven by cancer-induced inflammation, may influence long-term survival outcomes following adjuvant therapy. These biomarkers have potential for guiding future clinical trials, enabling personalized treatment strategies, and ultimately improving the management and prognosis of patients with pancreatic cancer.