waiting room usedA novel imaging technique showed substantially higher detection rates of prostate-specific membrane antigen (PSMA) in patients with biochemical recurrence after radical prostatectomy, when compared to other imaging methods, according to a recent study in The Journal of Nuclear Medicine.

Researchers also found that Ga-68-PSMA-ligand PET/CT identified a large number of positive findings in the clinically important range of low prostate-specific antigen values (<0.5ng/mL).

According to Centers for Disease Control, prostate cancer is the second most common cancer among men in the United States and remains one of the leading causes of cancer death among men of all races. While treatment and survival after recurrence depend on many factors, early detection of the recurrence can strongly influence further clinical management.

“The study is the first to examine this highly promising PET tracer in the use of a homogeneous patient collective consisting of only those with biochemical recurrence after radical prostatectomy,” said Matthias Eiber, MD, corresponding author of the study. “It found superb detection rates compared to other tracers, like choline, or imaging modalities, like [magnetic resonance imaging]. For patients, this means that the referring urologist can receive earlier and more precise information about the site and extent of metastatic disease. Physicians will also be better able estimate whether a PSMA-PET scan might be useful in a specific setting.”

The study evaluated 248 patients with biochemical recurrence (median PSA level of 1.99ng/mL and a range of 0.2-59.4ng/mL) after radical prostatectomy. Study participants were given contrast-enhanced PET/CT after injection of 155±27MBq Ga-68-PSMA-ligand, and detection rates were then correlated with PSA-level and PSA-kinetics. Researchers evaluated influencing factors, such as anti-hormonal treatment and primary Gleason score, as well as the contribution of PET and morphological imaging to the final diagnosis.

For 222 (89.5 percent) of the patients, the test detected higher than normal levels of PSMA. Detection rates increased with higher PSA-velocity, however no significant correlation could be made for PSA doubling-time.

Furthermore, Ga-68-PSMA-ligand PET (compared to CT) exclusively provided pathological findings in 81 (32.7 percent) patients, and in 61 (24.6 percent) patients, it exclusively identified additional involved regions. For those with a higher Gleason score (?7 versus ?8), detection efficacy was significantly increased (P = 0.0190).

“These findings will certainly enhance the use of PET in the diagnostic workup of patients with recurrent prostate cancer,” Eiber said. “When regulatory hurdles and reimbursement issues are overcome, this tracer might gain significant acceptance beyond Europe.”

In addition to Eiber, authors of the article “Evaluation of Hybrid 68Ga-PSMA-ligand PET/CT in 248 Patients with Biochemical Recurrence after Radical Prostatectomy” include Tobias Maurer, Michael Souvatzoglou, Ambros J Beer, Alexander Ruffani, Bernhard Haller, Hubert Kübler, Uwe Haberkorn, Michael Eisenhut, Hans-Jürgen Wester, Jürgen E Gschwend, and Markus Schwaiger.

For more information, visit The Journal of Nuclear Medicine.

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