PSMA positron emission tomography-computed tomography (PSMA PET-CT) offers a more accurate way to stage men with high-risk localized prostate cancer than conventional imaging, according to investigators.

“PSMA PET-CT is a suitable replacement for conventional imaging, providing superior accuracy, to the combined findings of CT and bone scanning,” Michael S. Hofman, MBBS, of the Peter MacCallum Cancer Centre in Victoria, Australia, and colleagues concluded in a paper published in The Lancet.

In a phase 3 trial, Dr Hofman and his collaborators studied 300 men with high-risk localized prostate cancer being considered for radical prostatectomy or radiotherapy with curative intent. Investigators randomly assigned the men to undergo conventional imaging with CT and bone scans (152 patients) or gallium-68 PSMA-11 PET-CT (148 patients). The study had a crossover design whereby men who had no more than 2 unequivocal distant metastases on first-line imaging underwent second-line imaging with the other imaging modality.

PSMA PET-CT demonstrated 27% greater accuracy than conventional imaging (92% vs 65%) in detecting pelvic nodal or distant metastases, the investigators reported. Compared with conventional imaging, PSMA PET-CT had greater sensitivity (85% vs 38%) and specificity (98% vs 91%).

First-line PSMA PET-CT led to more management changes than conventional imaging (28% vs 15%) and fewer equivocal findings (7% vs 23%).

In addition, conventional imaging was associated with greater radiation exposure than PSMA PET-CT (19.2 vs 8.4 mSy).

Among patients who underwent second-line imaging, management change occurred in 27% of patients following PSMA PET-CT compared with 5% of those following conventional imaging.

“Collective data from this prospective imaging study and other series provides data that PSMA PET-CT is better than and can replace conventional imaging with CT and bone scan for staging men with high-risk prostate cancer before surgery or radiotherapy with curative intent. Existing guidelines should be reviewed in light of these findings,” the authors wrote. “Further health-economic analyses are required to support potential reimbursement to enable widespread access to PSMA PET-CT for men.”

In an accompanying editorial, Caroline M. Moore, MD, of University College London, observed, “The introduction of novel imaging into routine practice requires careful assessment of the potential burden to individuals and society, taking into account the resulting changes in treatment.”

She said an economic analysis of the potential effect of replacing conventional staging with PSMA PET-CT “will be crucial in assessing the feasibility of widespread use of PSMA PET-CT in men being considered for radical treatment for high-risk prostate cancer.”

References

Hofman MS, Lawrentschuk N, Francis RJ, et al. Prostate-specific membrane antigen PET-CT in patients with high-risk prostate cancer before curative-intent surgery or radiotherapy (proPSMA): a prospective, randomised, multicentre study. Lancet.

Moore C. Prostate-specific membrane antigen PET-CT before radical treatment. Lancet.