By Robb Murray
Free Press Staff Writer
MANKATO — For many men who have defeated prostate cancer, one of their biggest concerns is whether it will come back.
For the most part, the technology available can only detect its recurrence after it’s already dangerous again.
But a new Mayo Clinic breakthrough in early detection of prostate cancer reoccurrence could mean extra years for the lives of the 1 in 6 men who at some point in their life will be dealing with the deadly disease.
The breakthrough involves a new test available to all men that can catch prostate cancer recurrence months — even years — quicker than traditional methods. The only catch is that the only place in the world you can get that test is in Rochester.
Mayo’s new test is powered by high-end chemistry and radioactive elements.
Here’s how it works: Traditionally, doctors have had to monitor prostate-specific-antigen, or PSA levels. Elevated levels could mean cancer has returned, but it’s not a given. The problem is that the elevated levels themselves aren’t solid indicators that cancer has returned. Very high levels are. But at that point, the cancer may already have a foothold that could be dangerously solid.
The new technique — which has the potential to give doctors a clear picture of recurring cancer long before a PSA level check — involves an injection of a nutrient called choline, which all cells need to grow. Cancer cells, however, gobble it up faster than normal cells. Before injecting it, radiologists infuse the choline with a radioactive isotope.
After the injection, the patient is run through a PET scan. But they’ve got to be run through the scan within minutes after the radioactive isotope comes into the picture. That isotope has a 20-minute half-life — which mean it breaks down by half every 20 minutes. By the time the scan takes place, there remains a fraction of the original infusion — but it’s enough.
The isotope emits gamma rays that are picked up by the scan. In cases of prostate cancer recurrence, so-called “hot spots” will be visible.
Mayo’s new method was featured in the medical journal CA: A Cancer Journal for Clinicians. The article, which examined new advances using imaging to diagnose and treat cancer, called choline PET scanning “promising.”
This entire process is exclusive to Mayo. Only in the last few months did they get approval from the U.S. Food and Drug Administration to do this testing. FDA approval is crucial to any type of medical testing. Without it, most insurance companies and Medicare or Medicaid won’t cover it. And these tests are costly.
Stephen Thome, an oncologist with Mayo Clinic Health System in Mankato, said they’ve already sent Mankato-area patients to Rochester for choline PET scans. And patients who go to Rochester, he said, don’t have to worry about records transferring. Mayo is all digital, and any Mayo patient from Mankato will have their records available to Mayo Clinic radiologists.
Post scan, Mankato-area patients can have all their care handled in Mankato. The only trip they need to make to Rochester is for the scan.
For now, the choline PET scan has only been approved for prostate cancer. But Thome said that’s only because this was the first kind of tumor that has been vetted for FDA approval. It’s likely that this technology will be tested to see if it will work on other forms of cancer. He said there’s already talk about collaborating with scientists who work with ovarian cancer.