Ga-68 Dotatate PET/CT Improves Detection of Gastroenteropancreatic Neuroendocrine Tumors


Key Points

  • Ga-68 dotatate PET/CT provided superior detection of gastroenteropancreatic neuroendocrine tumors.
  • Lesions were detected even in the absence of biochemical evidence of disease.

In a study reported in the Journal of Clinical Oncology, Sadowski et al found that Ga-68 dotatate positron-emission tomography/computed tomography (PET/CT) improved detection of gastroenteropancreatic neuroendocrine tumors compared with 111In-pentetreotide single-photon emission computed tomography/computed tomography (SPECT/CT) and anatomic imaging with CT and/or magnetic resonance imaging (MRI).

Neuroendocrine tumors express somatostatin receptors that can be targeted with radiolabeled peptides for imaging and treatment purposes. Ga-68 dotatate imaging uses somatostatin analogs labeled with the positron-emitting isotope 68Ga (68Ga-DOTA peptides).

Study Details

The study included 131 patients with known or suspected gastroenteropancreatic neuroendocrine tumors based on CT, MRI, or PET imaging; biochemical evidence of gastroenteropancreatic neuroendocrine tumors; or familial predisposition to neuroendocrine tumors. Patients underwent Ga-68 dotatate PET/CT, 111In-pentetreotide SPECT/CT, and multiphasic CT scan and/or MRI in addition to comprehensive biochemical testing. The primary outcome measure was the detection of lesions.

Detection of Lesions

The percentage of lesions detected was 95.1% (95% confidence interval [CI] = 92.4%–96.8%) with Ga-68 dotatate PET/CT (average maximum standardized uptake value = 65.4, range = 6.9–244) vs 45.3% (95% CI = 37.9%–52.9%) with CT/MRI anatomic imaging and 30.9% (95% CI = 25.0%–37.5%) with 111In-pentetreotide SPECT/CT (P < .001 for both comparisons).

In 14 patients with an unknown primary tumor, Ga-68 dotatate PET/CT identified the primary lesion in 4, compared with 0 using 111In-pentetreotide SPECT/CT and 2 using CT/MRI. Compared with histopathology, primary gastroenteropancreatic neuroendocrine tumor, positive lymph nodes, and distant metastases were correctly identified in 63.7% of 113 lesions with Ga-68 dotatate PET/CT, compared with 22.1% using 111In-pentetreotide SPECT/CT, and 38.9% using anatomic imaging. On the basis of Ga-68 dotatate PET/CT findings, changes in management recommendations were made for 43 patients (32.8%). In patients with carcinoid symptoms and negative biochemical testing, Ga-68 dotatate PET/CT detected lesions in 65.2% of patients, with 40% of these lesions not being detected by either 111In-pentetreotide SPECT/CT or CT/MRI.

The investigators concluded: “Ga-68 dotatate PET/CT imaging provides important information for accurate staging of gastroenteropancreatic neuroendocrine tumors and selection of appropriate treatment interventions even in the absence of biochemical evidence of disease in symptomatic patients.”

The study was supported by the National Cancer Institute and the National Institute of Diabetes and Digestive and Kidney Diseases.

Electron Kebebew, MD, of the National Cancer Institute, is the corresponding author of the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.