DOTATATE PET/CT imaging pinpoints neuroendocrine tumors

Last Updated: 2016-01-07

By David Douglas

NEW YORK (Reuters Health) - Imaging with gallium-68 DOTATATE positron emission tomography (PET) and computed tomography (CT) offers advantages over other methods of detecting gastro-entero-pancreatic neuroendocrine tumors (GEPNETs), according to researchers at the National Institutes of Health.

In a December 28 online paper in the Journal of Clinical Oncology, Dr. Electron Kebebew, of the National Cancer Institute, Bethesda, Maryland, and colleagues note that the approach is still investigational and "there have been no large prospective studies with comprehensive biochemical screening to evaluate its clinical utility when specifically focused on GEPNETs."

To do so, the team enrolled 131 patients with suspected or known GEPNETs who underwent 68Ga-DOTATATE imaging. They compared that with current Food and Drug Administration-approved imaging modalities, 111In-pentetreotide single-photon emission computed tomography (SPECT/CT), CT, and/or magnetic resonance imaging (MRI).

68Ga-DOTATATE PET/CT imaging detected 95.1% of lesions, anatomic imaging detected 45.3%, and 111In-pentetreotide SPECT/CT detected 30.9%.

In four of 14 patients, compared to histopathology, proportions for correct detection of a previously unknown primary tumor, primary GEPNET, lymph node, and distant metastases were 63.7% for 68Ga-DOTATATE PET/CT compared to 22.1% for 111In-pentetreotide SPECT/CT and 38.9% with anatomic imaging.

Because of these findings, say the investigators, 43 of the patients (32.8%) had a change in management recommendation. Moreover, in patients with carcinoid symptoms but negative biochemical testing, 68Ga-DOTATATE PET/CT detected lesions in 65.2%. Of these, 40% were detected neither by anatomic imaging nor by 111In-pentetreotide SPECT/CT.

Among limitations of the study, say the investigators, is that "we do not have histopathologic proof for every lesion detected; thus, false positive results are possible." Also it is not known whether "the therapeutic options selected on the basis of 68Ga-DOTATATE PET/CT imaging resulted in improved long-term patient outcome."

However, the researchers conclude that the approach is more sensitive for staging and detecting unknown primary GEPNETs than are the others and that "it should be implemented in the initial management and follow-up of patients with GEPNETs as it can significantly optimize patient care decisions."

Commenting on the findings by email, Dr. Ebrahim S. Delpassand, chairman and medical director at Excel Diagnostics and Nuclear Oncology Center, Houston, Texas, told Reuters Health "This is a nicely written manuscript by our colleagues at NIH on an important test for patients with NET."

"The results match other previously published literature on this topic," and he concluded, "This test will be a new gold standard for diagnostic management of patients with NET."

Dr. Kebebew was unable to respond to requests for comment.

The authors reported no external funding or disclosures.

SOURCE: bit.ly/1Rlwj9B

J Clin Oncol 2015.