Are RECIST criteria sufficient to assess response to therapy in neuroendocrine tumors?

Material and Methods Within the group of 47 patients treated with peptide receptor radionuclide therapy (PRRT), four patients were chosen: three with inoperable tumors without liver metastases and one with two lesions in the pancreas and metastases. Results In all patients, after PRRT, the changes in the sum of the longest diameters of tumors were between −1% and −21%, resulting in stable disease reported [strict Response Evaluation Criteria in Solid Tumors (RECIST)]. But the measurements of tumor volume and attenuation in computed tomography and the tumor to nontumor ratio in somatostatin receptor scintigraphy resulted in different response assessments. Conclusions The RECIST standard may be not sufficient to properly assess the therapy response in patients with neuroendocrine tumors.