A new imaging (PET scan) agent used to locate occult prostate cancer cells when PSA is rising

This study examined the performance of a new radioactive tracer, ¹¹ C-Choline, which is used for PET-CT scans, for its ability to detect prostate cancer distribution and extent after initial therapy. The tracer performed well in men with a recurrence and increased the frequency of tumor detection, compared to standard imaging methods.  

Rising levels of Prostate Specific Antigen (PSA) in patients after primary treatment for prostate cancer is referred to as “biochemical recurrence”. It may indicate a recurrence (return) of the disease but does not provide tumor location. A tracer is an injected (intravenous) radioactive material used to intensify tumor signals during PET-CT scans, thereby exposing and locating them. Location of cancer cells on imaging studies is usually followed by a biopsy (tissue sample and microscopic examination) to confirm a recurrence. The ¹¹ C-Choline was licensed (since 2012) for use in patients with a biochemical recurrence.

The authors of this article examined the medical records of 176 men with a biochemical recurrence, who had both standard imaging studies and the ¹¹ C-Choline PET-CT. Of the 176 scans, 56 (32%) were useful as defined by the ability to identify tumors not detected by conventional imaging. The optimal PSA level for tumor detection was 2.0ng/ml.

In summary, this study shows that, compared to conventional imaging techniques, ¹¹ C-Choline substantially increases the sensitivity of PET/CT scans for detection of prostate cancer cells following a biochemical recurrence. This implies that ¹¹ C-Choline-based PET scans could be effective when PSA levels are much lower than the concentration required for normal imaging methods.

And yet, this study is limited by the fact that it was based on medical records (retrospective study) rather than conducted as a prospective clinical trial.

If your PSA levels are rising after initial treatment for prostate cancer, talk to your doctor about having a ¹¹ C-Choline PET scan.