A study recently published in The Journal of Nuclear Medicine may have found a better PET tracer for imaging prostate cancer.

Researchers at the University of Michigan compared the effectiveness of the current standard, 11C-choline, to Carbon-11 labeled sarcosine (11C-sarcosine).

Dr. Morand Piert, professor of radiology at the university, explained that 11C-sarcosine was considered for prostate cancer imaging because metabolomic data indicated strongly elevated tissue levels in localized prostate cancer, and particularly in metastatic disease.
Preclinical experiments involving mice revealed that tumor-to-background ratios obtained from 11C-sarcosine PET were much higher than those obtained with 11C-choline. They then performed the first 11C-sarcosine PET/CT scan on a human with prostate cancer and found it can generate high-contrast images.

The researchers concluded that 11C-sarcosine is a viable PET tracer for imaging prostate cancer and has potential benefits over 11C-choline.

Aside from skin cancer, prostate cancer is the most prevalent cancer among men in the U.S. The American Cancer Society estimates that there will be about 161,360 new cases of prostate cancer in 2017.

Sarcosine plays a vital role in the aggressiveness and progression of the disease. It's an excellent imaging target because it enters cells through proton-coupled amino acid transporters (PAT), which are overexpressed in solid tumors.

11C-sarcosine could also be used for identifying and characterizing other types of cancer. According to the researchers, that's because it's the first tracer that can interrogate the activity of PATs.

In the brain, PATs are involved in the neuronal amino acid transport process and in the intestinal tract, certain PATs act as nutrients and drug transporters.

The researchers also noted that PAT function has been connected to the amino acid-sensing engine that drives the activation of an important target for anti-cancer drugs. They believe that elevated 11C-sarcosine may be potentially useful for monitoring cancer treatments, but more research is needed to confirm that.

"The tracer could be useful for malignancies with elevated PAT expression," said Piert. "However, since the PAT expression is unknown for most malignancies, we honestly don't know the answer to the question."

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