Several authors reported the superiority of ⁶⁸Ga-DOTANOC PET/CT to conventional imaging (CI) for the assessment of neuroendocrine tumors (NET). However, the detection of a higher number of lesions is not necessarily followed by a modification of disease stage or therapeutic approach. The aim of this study was to assess the impact of ⁶⁸Ga-DOTANOC PET/CT on the clinical management of NET patients. Methods: The study included 90 patients with pathologic confirmation of NET, CT performed within a month of ⁶⁸Ga-DOTANOC PET/CT, and a follow-up period of at least 1 y. PET/CT results were compared with CI results. As a standard of reference to finally evaluate PET results, clinical and imaging follow-up data were used. To assess the clinical impact of PET findings, all referring physicians were contacted after PET and asked about how patients were managed. Stage or therapy modifications were independently recorded, and the overall impact was evaluated patient by patient if PET results either affected therapy or caused a change in disease stage. Results: Considering PET/CT and CI concordant cases (47/90 [52.2%]), PET findings affected the therapeutic management in 17 of 47 (36.2%) patients. Although PET did not result in modification of disease stage, ⁶⁸Ga-DOTANOC detected a higher lesion number in most patients. PET/CT and CI findings were discordant in 42 of 90 (46.7%) patients: PET resulted in a modification of stage in 12 patients (28.6%) and affected the treatment plan in 32 patients (76.2%). PET and CT were both equivocal in 1 patient (1/90). Considering all cases, ⁶⁸Ga-DOTANOC PET/CT affected either stage or therapy in 50 of 90 (55.5%) patients. The most frequent impact on management (27 patients) was the initiation or continuance of peptide receptor radionuclide therapy, followed by the initiation or continuance of somatostatin analog medical treatment (7 patients) and referral to surgery (6 patients). PET prevented unnecessary surgery in 6 patients and excluded from treatment with somatostatin analogs 2 patients with NET lesions that did not express somatostatin receptors. Less frequent impacts on management included the initiation of radiotherapy (1 patient), further diagnostic investigation (1 patient), and liver transplantation (1 patient). Conclusion: ⁶⁸Ga-DOTANOC PET/CT either affected stage or caused a therapy modification in more than half the patients, thus confirming the clinical role of PET in the management of NET.

Despite the fact that several studies have been published regarding the prognostic factors of neuroendocrine tumors (NETs), there are some cases in which available data are not sufficient to predict disease progression and to define a correct therapeutic approach. To our knowledge, the role of maximum standardized uptake value (SUVmax) as a prognostic factor has never been studied in NET patients. Therefore, we prospectively investigated whether ⁶⁸Ga-[1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-octreotide (⁶⁸Ga-DOTANOC) PET SUVmax could be used as an accurate noninvasive marker for disease prognosis. Methods: Forty-seven patients with NETs were studied with ⁶⁸Ga-DOTANOC PET. All patients underwent a baseline visit and laboratory and radiologic examinations. Follow-up was performed in all cases. Results: SUVmax was significantly higher in patients with pancreatic NET and in those with well-differentiated NETs. Moreover, SUVmax was significantly higher in patients with an elevated expression of 2A-somatostatin receptor. During the follow-up, the disease was stable or presented a partial response in 25 patients, and in 19 cases the disease progressed. The patients with stable disease or a partial response had an SUVmax significantly higher than did those in the progressive disease group, with the best cutoff ranging from 17.9 to 19.3. At univariate and multivariate analysis, the significant positive prognostic factors were well-differentiated NET, an SUVmax of 19.3 or more, and a combined treatment with long-acting somatostatin analogs and radiolabeled somatostatin analogs. Conclusion: We demonstrated, for the first time to our knowledge, that ⁶⁸Ga-DOTANOC PET SUVmax correlates with the clinical and pathologic features of NETs and is also an accurate prognostic index.