Impact of the FDG-PET in the management of patients with pancreatic cancer

Abstract

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Objectives: Although FDG-PET has been used for the management of patients with adenocarcinoma of the pancreas, there are limited number of reports in the literature regarding the initial diagnosis of the primary cancer and the role of this technique in follow-up period after surgery and other interventions. Therefore, the aim of this study was to assess the role of PET in this population.

Methods: Fifty-five FDG-PET studies in 47 patients (mean age: 60.0 ±11.1; 22 F, 25 M) with adenocarcinoma of the pancreas were retrospectively analyzed. Twenty-three patients were examined before therapy and assessed for metastasis while 32 were evaluated because of had suspicion for recurrence and/or distant metastasis because of clinical and laboratory findings. Whole body FDG-PET images were obtained approximately 60 minutes after the intravenous administration of (5.2 Mbq / kg of body weight) FDG. The degree of FDG uptake of the lesion was assessed by calculating the maximum standardized uptake value (SUVmax). The results were compared with those of the clinical follow-up and surgical findings.

Results: In the 23 patients with the primary pancreatic cancer at the initial presentation, PET demonstrated 20 primary lesions while CT showed 22 of them. In this group, PET showed 10 lymph nodes, 7 distant metastases while radiological studies detected 11 lymph nodes and 5 distant metastatic lesions. The SUVmax of the primary lesions and the metastatic lesions were 5.3±1.7 and 4.0±2.3, respectively. Among the 32 PET studies performed in the follow up period, PET showed 7 recurrences in pancreatic bed and 13 lymph node and 13 distant metastatic lesions. In contrast in 26 patients, CT/MRI studies showed 4 recurrences, 6 lymph node and 6 distant metastatic lesions. In addition, CT was found to be positive for 1 recurrent lesion, 1 lymph node metastasis and 1 distant metastatic lesion which were not FDG avid because of radiotherapy to these sites. Therefore, they were considered to be false positive for CT in that clinical setting. Three recurrent and 2 distant metastatic lesions which were read as suspicious for cancer on CT/MRI were clearly visualized with high SUV on PET. The SUVmax of the recurrent lesions and the metastatic lesions were 3.1±0.8 and 5.4±3.3, respectively.

Conclusions: These data demonstrated that PET is more specific but less sensitive than CT for detecting primary pancreatic cancers but is more accurate for visualizing recurrent and distant metastatic lesions. Therefore, FDG-PET plays a complementary role to that of the structural imaging techniques such as CT-MRI following the initial diagnosis when recurrence and/or metastasis are suspected. Also, FDG-PET is of value in monitoring response to treatment in this population.