Survival times vary among patients with neuroendocrine tumors (NETs)—even among those with the same site, stage, and grade of primary tumor. This makes it difficult to select treatment for patients with unresectable NETs, because some patients can survive decades without treatment. 68Gallium-DOTATATE positron emission tomography with computed tomography (68Ga-DOTATATE PET/CT) is a sensitive imaging technique for detection of NETs. We investigated the prognostic accuracy of 68Ga-DOTATATE PET/CT analysis of tumor volume in patients with NETs.