Diagnostic performance and impact on patient management of [(68)Ga]Ga-DOTA-TOC PET/CT in colorectal neuroendocrine tumors derived from hindgut

The main purpose of this retrospective study was to determine the diagnostic performance of [(68)Ga]Ga-DOTA-D-Phe1-Try3-octreotide(DOTA-TOC) positron emission tomography/computed tomography (PET/CT) in patients with well-differentiated colorectal Neuroendocrine Tumours (NETs) originating from the hindgut. The other aims were to assess the impact of the examination on patient management and to analyze the results of 2-[(18)F]FDG and/or 6-[(18)F]FDOPA PET/CT when they were performed. [(68)Ga]Ga-DOTA-TOC PET/CT and clinical data from 30 patients with biopsy-proven well-differentiated NETs originating from the hindgut were retrospectively reviewed and analyzed by comparing the [(68)Ga]Ga-DOTA-TOC PET/CT findings with pathological and/or follow-up data. We also compared the [(68)Ga]Ga-DOTA-TOC PET/CT results with 2-[(18)F]FDG and/or 6-[(18)F]FDOPA PET/CT results in 6 patients. The impact on management was determined in hindsight by comparing the patient management decided before and after the TEP examination based on data from multidisciplinary team meetings. On a patient basis, [(68)Ga]Ga-DOTA-TOC PET/CT was accurate in 30 of the 30 examinations. [(68)Ga]Ga-DOTA-TOC PET/CT correctly identified the primary tumor in all patients with primary tumors not resected before the examination and allowed the detection of unexpected distant metastases in 36% of the patients referred for initial staging. [(68)Ga]Ga-DOTA-TOC PET/CT findings affected patient management in 57% of cases with generally major intermodality changes. Intraindividual comparison of the results of the different PET radiopharmaceuticals showed a clear superiority of [(68)Ga]Ga-DOTA-TOC PET/CT considering both the number of lesions and the intensity of uptake. [(68)Ga]Ga-DOTA-TOC PET/CT is an accurate imaging modality for the assessment of well-differentiated colorectal NETs that highly impact patient management. Thus, we suggest that [(68)Ga]Ga-DOTA-TOC PET/CT be employed as a first choice for the assessment of these tumors in nuclear medicine.