(18)fluorodeoxyglucose positron emission tomography in the management of patients with suspected pancreatic cancer

Objective To assess the accuracy and clinical impact of (18)fluorodeoxy-glu cose-positron emission tomography (18FDG-PET) on the management of patients with suspected primary or recurrent pancreatic adenocarcinoma, and to asse ss the utility of (18)FDG-PET in grading tumor response to neoadjuvant chem oradiation. Summary Background Data The diagnosis, staging, and treatment of pancreatic cancer remain difficult. Small primary tumors and hepatic metastases are o ften not well visualized by computed tomographic scanning (CT), resulting i n a high incidence of nontherapeutic celiotomy and the frequent need for "b lind resection." In addition, the distinction between local recurrence and nonspecific postoperative changes after resection can be difficult to ascer tain on standard anatomic imaging. (18)FDG-PET is a new imaging technique t hat takes advantage of increased glucose metabolism by tumor cells and may improve the diagnostic accuracy of preoperative studies for pancreatic aden ocarcinoma. Methods Eighty-one (18)FDG-PET scans were obtained in 70 patients undergoin g evaluation for suspected primary or recurrent pancreatic adenocarcinoma. Of this group, 65 underwent evaluation for suspected primary pancreatic can cer. Nine patients underwent (18)FDG-PET imaging before and after neoadjuva nt chemoradiation, and in eight patients (18)FDG-PET scans were performed f or possible recurrent adenocarcinoma after resection. The (18)FDG-PET image s were analyzed visually and semiquantitatively using the standard uptake r atio (SUR). The sensitivity and specificity of (18)FDG-PET and CT were dete rmined for evaluation of the preoperative diagnosis of primary pancreatic c arcinoma, and the impact of (18)FDG-PET on patient management was retrospec tively assessed. Results Among the 65 patients evaluated for primary tumor, 52 had proven pa ncreatic adenocarcinoma and 13 had benign lesions. (18)FDG-PET had a higher sensitivity and specificity than CT in correctly diagnosing pancreatic car cinoma (92% and 85% vs. 65% and 62%). Eighteen patients (28%) had indetermi nate or unrecognized pancreatic masses on CT clarified with (18)FDG-PET. Se ven patients (11%) had indeterminate or unrecognized metastatic disease cla rified with (18)FDG-PET. Overall, (18)FDG-PET suggested potential alteratio ns in clinical managemet in 28/65 patients (43%) with suspected primary pan creatic adenocarcinoma. Of the nine patients undergoing (18)FDG-PET imaging before and after neoadjuvant chemoradiation, four had evidence of tumor re gression by PET, three showed stable disease, and two showed tumor progress ion. CT was unable to detect any response to neoadjuvant therapy in this gr oup. Eight patients had 18FDG-PET scans to evaluate suspected recurrent dis ease after resection. Four were noted to have new regions of (18)FDG-uptake in the resection bed; four had evidence of new hepatic metastases. All pro ved to have metastatic pancreatic adenocarcinoma. Conclusions These data confirm that (18)FDG-PET is useful in the evaluation of patients with suspected primary or recurrent pancreatic carcinoma. (18) FDG-PET is more sensitive and specific than CT in the detection of small pr imary tumors and in the clarification of hepatic and distant metastases. (1 8)FDG-PET was also of benefit in assessing response to neoadjuvant chemorad iation. Although (18)FDG-PET cannot replace CT in defining local tumor rese ctability, the application of (18)FDG-PET in addition to CT may alter clini cal management in a significant fraction of patients with suspected pancrea tic cancer.