C-11 Cho PET/CT helps localize prostate cancer recurrence

Findings of a study by researchers in Italy suggest C-11 choline PET/CT could diagnose prostate cancer recurrence sooner than transrectal ultrasound, CT, MRI, or bone scintigraphy in patients who have undergone radical prostatectomy.

Up to 30% of patients with prostate cancer who have undergone radical prostatectomy will relapse within 10 years. The statistics are more discouraging for those treated with externalbeam radiotherapy, as more than half will experience some form of recurrence within five years.

Prostate-specific antigen (PSA) levels remain the most reliable way to determine recurrence. Accurate characterization, staging, and localization of disease become the most crucial steps for management when biochemical relapse is confirmed. However, conventional imaging modalities, such as transrectal ultrasound, CT, MRI, and bone scintigraphy, have limited value.

According to a research group from the University of Bologna led by nuclear physician Dr. Paolo Castellucci, PET/ CT with C-11 choline has emerged as a promising alternative.

“In most patients with biochemical relapse after radical prostatectomy, conventional imaging methods often return false-negative results,” Castellucci said. “Our study found that for some patients, PET/CT with choline can improve the detection of cancer soon after PSA levels are measured.”

Castellucci and colleagues retrospectively evaluated 190 patients with biochemical relapse after radical prostatectomy who underwent C-11 choline PET/CT. Researchers classified patients by their PSA levels as well as PSA kinetic factors such as PSA velocity-the rate at which PSA levels change-and PSA doubling time.

The investigators found that detection of cancer recurrence with wholebody choline PET/CT in patients with biochemical relapse after prostatectomy correlates significantly with PSA levels and PSA kinetics. Results validated previous findings that suggest PSA kinetics improve detection, particularly in patients with low PSA levels. Findings appeared in the September issue of the Journal of Nuclear Medicine.

According to the U.S. National Cancer Institute, one in six men will be diagnosed with cancer of the prostate during his lifetime. This year alone, nearly 200,000 U.S. men will be diagnosed with the condition and more than 13% of them will die. The numbers are not much better in Europe, where incidence of the condition has recently increased and the mortality rate has reached about 30 patients per 100,000 cases, according to data from the European Society for Medical Oncology.

The analysis of PSA kinetics could improve patient selection for PET/CT scanning, reduce false-negative scans, and increase detection rates. Although further studies are needed to confirm these theories, whole-body C-11 choline PET/CT imaging has the potential to become a one-stop test to identify those patients with early relapse who have the best chances for curative treatment, investigators said.

“This enables physicians to tailor treatment to individual patients in the early stages of recurrence, thus increasing their chances of recovery,” Castellucci said.