SPECT/CT can distinguish lymph nodes in thyroid cancer patients

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Researchers were able for the first time to accurately distinguish between cancerous cells in regional lymph nodes and normal residual thyroid tissue directly after surgery, according to a study in this month’s issue of the Journal of Nuclear Medicine.

Researchers from the University of Erlangen-Nürnberg in Germany, reported the results of a study using a hybrid SPECT/CT camera to determine and locate the spread of cancer cells to nearby lymph nodes.

According to the investigators, the demonstration or exclusion of cancer spread in regional lymph nodes plays a major role in treating the disease since all patients with lymph node metastases are considered to be at high risk for recurrence.

Currently, patients with differentiated thyroid carcinoma (DTC) who have had their thyroid removed are treated with radioactive iodine, which effectively zeros in on and kills any remaining cancerous thyroid cells. Radioiodine is taken up by any thyroid tissue not removed by surgery, including cancerous cells spreading to other body parts, such as lymph nodes. In addition to emitting electrons that destroy the tissue harboring the radionuclide, radioactive iodine emits photons suitable for imaging.

In the study, 57 patients received radioiodine therapy. Afterwards, a SPECT/CT camera was rotated around the patients at a variety of angles to capture where the radioactivity was occurring.
"With SPECT/CT imaging, we were able to determine tumor spread much earlier than before," said Daniela Schmidt, MD, a co-author of the study. "Earlier detection will lead to earlier individualized treatment of this potentially deadly cancer."

The researchers also reported that this information led to a revision of the original diagnosis in 35 percent of the study participants. The images reclassified as benign six of 11 lesions that had been considered lymph node metastases and 11 of 15 lesions considered to be indeterminate.

“Our data suggest that SPECT/CT should be used as a routine procedure in DTC patients at the first radioiodine treatment,” said Torsten Kuwert, MD, another co-author of the article. "By upstaging or downstaging disease, this hybrid imaging tool may alter the management of more than one-third of patients with the disease."

According to the American Cancer Society, DTC is the most common form of thyroid cancer and one of the success stories in the war on cancer. Since the advent of radioiodine therapy, it has been considered one of the more curable cancers. In 2009, about 37,340 new cases of thyroid cancer will be diagnosed in the United States. Of the new cases, about 28,410 will occur in women, and 8,930 in men.