68Ga-DOTANOC PET/CT clinical impact in patients with neuroendocrine tumors

Several authors reported the superiority of (68)Ga-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 (68)Ga-DOTANOC PET/CT on the clinical management of NET patients.

The study included 90 patients with pathologic confirmation of NET, CT performed within a month of (68)Ga-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.

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, (68)Ga-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, (68)Ga-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).

(68)Ga-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.