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.