Imaging Cancer’s Return

Prostate cancer imaging agent that spots recurrence wins FDA approval

(RxWiki News) After prostate cancer patients receive treatment, they still run the risk of the disease coming back. A newly approved imaging agent offers a way to detect recurrence earlier.

The US Food and Drug Administration has approved a new imaging agent—Choline C 11—that doctors can use to more clearly identify prostate cancer return at an earlier stage.

"Find out about the latest imaging techniques."

Developed by the Mayo Clinic in Rochester, Minnesota, Choline C 11 is a radioactive form of the vitamin choline. Choline is in the B vitamin family and found in high concentration in egg yolks.

“Choline C 11 Injection provides an important imaging method to help detect the location of prostate cancer in patients whose blood tests suggest recurrent cancer when other imaging tests are negative,” said Charles Ganley, MD, director of the Office of Drug Evaluation IV in FDA’s Center for Drug Evaluation and Research, in an FDA press release.

Cancer cells take up more of the new agent than normal cells. When a small amount of Choline C 11 is injected in a patient, a PET scanner and computer can provide detailed images of areas in the body where the agent is concentrated.

PET stands for positron emission tomography, and the technology uses radiation and nuclear medicine to produce 3-D color images of how organs and tissues are functioning inside the body.

Prostate cancer patients have different options when it comes to treatment, including surgery, radiation therapy, hormonal therapy and chemotherapy. Sometimes, cancer cells escape the treatment and they continue to grow. That’s why prostate cancer patients are advised to visit their doctor for regular check-ups after treatment to see if the cancer has returned.

The Mayo Clinic advises that this choline technique can be used when other imaging approaches, such as bone scintigraphy, computerized tomography or magnetic resonance imaging, are non-informative.

If a potential cancerous site is identified, a biopsy and lab tests can be performed to verify if the cancer has come back.

The safety and effectiveness of Choline C 11 Injection were verified by the FDA’s systematic review of published study reports. Four independent studies examined a total of 98 patients with elevated blood prostate specific antigen (PSA) levels but no sign of recurrent prostate cancer from conventional imaging. After PET imaging with Choline C 11, the patients underwent tissue sampling of the abnormalities detected on the PET scans.

In each of the four studies, at least half the patients who had abnormalities detected on PET scans also had recurrent prostate cancer confirmed by tissue sampling of the abnormal areas.

The Mayo Clinic touts the approach for its accuracy and potential to spot recurring cancer earlier than other diagnostic approaches.

In most cases, cancerous tissue produces more PSA. Doctors typically image patients whose PSA levels are increasing after earlier treatment for prostate cancer.

With other diagnostic techniques, physicians have had to wait until a patient’s PSA levels rose to values between 20 to 30 ng/mL (nanograms per milliliter) to identify sites of recurrent prostate cancer.

The PET scanning with choline can be used when the PSA level is at 2 ng/m. Eugene Kwon, MD, urologist at the Mayo Clinic, said in a statement that this allows for cancer detection “...months or even years earlier than before. This technology also allows us to pinpoint the locations of recurrent cancer more accurately and permits us to develop more effective treatment strategies.”

Review Date: 
November 9, 2012