The September issue of The Journal of Nuclear Medicine published a study that shows that positron emission tomography (PET)/computer tomography (CT) scans using the imaging agent choline could detect recurring prostate cancer sooner than conventional imaging technologies in some men who have had prostatectomy.

Men who elect to have a radical prostatectomy to treat prostate cancer have a thirty percent (30%) chance of having the cancer reoccur. In the normal course of events a man’s prostate specific antigen (PSA) is monitored, post surgery, to detect a cancer recurrence. If there is a change in the PSA level, imaging is used to find where the cancer has returned.

The study evaluated the use of a PET/CT scans with a radioactive marker called Choline. Choline is a molecular imaging tool that has been shown to be more accurate than conventional imaging techniques such as CT, magnetic resonance imaging (MRI) and bone scintigraphy in detecting recurrent prostate cancer.

“In most patients with biochemical relapse after radical prostatectomy, conventional imaging methods often return false-negative results, meaning that the imaging techniques fail to detect cancer that is present in the body,” said Paolo Castellucci, M.D., of the nuclear medicine unit, hematology-oncology and laboratory medicine department, Azienda Ospedaliero-Universitaria di Bologna Policlinico S. Orsola-Malpghi, University of Bologna, Italy, and lead author of the study. “Our study found that for some patients, PET/CT with choline can improve the detection of cancer soon after PSA levels are measured. This enables physicians to tailor treatment to individual patients in the early stages of recurrence, thus increasing their chances of recovery.”

This study was small, consisting of only 190 men post radical prostatectomy who showed biochemical (PSA) relapse. These men were grouped according to PSA levels and evaluated using choline PET/CT scans. Researchers also factored in PSA kinetic factors such as velocity, the rate at which PSA levels change, and the PSA doubling time.

The study found that whole body PET/CT imaging with choline is significantly better than conventional imaging technologies in detecting prostate cancer in patients with a biochemical relapse after radical prostatectomy. They also found there was a strong association between PET/CT detection of recurrent cancer, PSA levels, and PSA kinetics.

The authors cautioned that only men with a high probability of having a positive scan based on PSA levels and kinetics should undergo choline PET/CT scans, reducing the number of unnecessary choline PET/CT scans.

Our current scanning technologies are not adequate to find early prostate cancer recurrences. The continued development of more sensitive and accurate scans will help in identifying early reoccurrences of prostate cancer leading to better control of this deadly disease. Better control will hopefully lead to extended survival.

Journal references:
P. Castellucci, C. Fuccio, C. Nanni, I. Santi, A. Rizzello, F. Lodi, A. Franceshelli, G. Martorana, F. Manferrari, and S. Fanti, S. Sharp, B. Shulkin, M. Gelfand, S. Salisbury, W. Furman. Influence of Trigger PSA and PSA Kenetics on 11C-Choline PET/CT Detection Rate in Patients with Biochemical Relapse After Radical Prostatectomy. The Journal of Nuclear Medicine, September 2009

Joel T Nowak MA, MSW