New Imaging Agent Locates Even the Smallest Neuroendocrine Tumors
Neuroendocrine tumors (NETs) are considered the zebras of the cancer world because they behave so differently from other cancers. While they typically grow slowly, they often can often grow and spread stealth-like. NETs can be very small and develop anywhere in the body, such as the stomach, intestines, pancreas and lungs. And because they don’t show up on typical PET scans, finding them at early stages or detecting metastasis is difficult.
Positron Emission Tomography (PET) scans normally detect cancer by infusing patients with a glucose preparation and then identifying the body areas (cancer cells or a tumor) where glucose is consumed or metabolized abnormally fast. However, most NETs do not consume glucose rapidly.
A new agent, gallium-68 dotatate (Netspot®), recently FDA-approved and available at Roswell Park, can be used as a PET tracer instead of the glucose to identify carcinoid tumors—even very small lesions—significantly better than any currently available imaging.
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How does it work?
While NETs don’t consume glucose like other cancers, their cells do have plenty of receptors for the hormone somatostatin, which regulates the endocrine system. Ga-68 dotatate is a radioactive lookalike of the hormone that can bind to the somatostatin receptors, and highlight the tumor on PET imaging.
How is it better than current testing methods?
This imaging approach significantly improves detection of NETs in three important ways:
- Faster process. Completed in a couple hours, this test is much quicker than the onerous three-day octreoscan (which uses a different radioactive drug and a gamma camera to measure the radio material over time).
- Better images. Because of the high sensitivity and combining of PET with CT, the physician gets a very clear, high-resolution image that can identify very small lesions that would otherwise be missed.
- Determines treatment. The improved imaging can help the oncologist choose optimal therapy, such as surgery versus systemic therapy. In addition, finding NETs in this manner means the patient would likely be eligible for a new treatment, called Peptide Receptor Radionuclide Therapy (PRRT)*, that uses hormone-tagged radiation to find the cancer cells, attach to them and deliver radiation directly to the cells. On January 29, 2018, the Food and Drug Administration (FDA) approved a form of PRRT, called lutetium Lu 177 dotatate (Lutathera®), for adult patients with advanced cancerous neuroendocrine tumors (NETs) that affect the pancreas or gastrointestinal tract, known as GEP-NETs. Lutetium Lu 177 dotatate is the first radioactive drug approved to treat these rare cancers. Roswell Park was one of the sites offering this innovative treatment on a compassionate use protocol.
Who should have this scan?
Physicians plan to use Netspot PET to diagnose neuroendocrine tumors, determine treatment options, plan surgery, and monitor for recurrence.
Are there any concerns about this test?
Patients who take long-acting somatostatin analogues (Sandostatin) should delay this test for 3-4 weeks after their last dose.