PSMA PET–based model may alleviate diagnostic challenges of ‘PSA gray zone’

New research suggests a model based on ⁶⁸Ga‑PSMA PET/CT imaging could enhance the predictive accuracy for clinically significant prostate cancer (csPCa) in patients in the ‘PSA gray zone’ of 4 to 10 ng/ml.¹

“The combination of ⁶⁸Ga-PSMA PET/CT and PSA tests provides a good performance-efficiency-diagnostic model to improve the net benefit and reduce the number of unnecessary prostate biopsies,” wrote lead study author Jinhui Yang, MD, and colleagues.

A study published in Cancer Imaging showed that a multivariate prediction model that incorporates ⁶⁸Ga‑PSMA PET/CT was 34% more effective than PSA testing alone and 27% more effective than multiparametric MRI (mpMRI) alone in detecting clinically significant prostate cancer (csPCa) in this patient population.¹

The study included 81 patients with total PSA (TPSA) levels between 4 and 10 ng/mL. The researchers wrote in their article that despite the widespread use of PSA testing for prostate cancer screening and early diagnosis, “…in the PSA gray zone of 4 to 10 ng/ml, the sensitivity and specificity for diagnosing PCa are limited, resulting in considerable number of unnecessary and invasive prostate biopsies, which may lead to potential overdiagnosis and overtreatment.”¹

All patients had prostate mpMRI, ⁶⁸Ga-PSMA PET/CT and systematic transrectal ultrasound (TRUS)/MRI/PET fusion-guided prostate biopsy, according to the study. The researchers noted that 29 men had csPCa and 52 men had non-csPCa.

The researchers found the multivariate prediction model, which included prostate volume (PV), free PSA (PSA)/TPSA and maximal standardized uptake value with ⁶⁸Ga-PSMA PET/CT, had a 92.7 area under the receiver operating characteristic curve (AUC) for predicting csPCa. In comparison, the study authors noted a 58.5 AUC for PSA alone, a 65.2 AUC for mpMRI alone and an 85% AUC for ⁶⁸Ga-PSMA PET/CT alone.¹

The predictive model incorporating ⁶⁸Ga-PSMA PET/CT also demonstrated an 86.21% sensitivity rate and an 86.54% specificity rate for predicting csPCa, according to the researchers.

“During the early diagnosis of csPCa, the ⁶⁸Ga-PSMA PET/CT SUVmax-based prediction model is a much better diagnostic method than PSA-based tests, as revealed by the larger AUC value and higher sensitivity and specificity of this test than those of PSA- and mpMRI-based tests,” wrote lead study author Jinhui Yang, MD, who is affiliated with the Department of Nuclear Medicine at Xiangya Hospital at Central South University in Changsha, China, and colleagues.¹

In comparison to patients with non-csPCa, the researchers noted that study participants with csPCa had larger PSA density (median PSAD of 0.21 ng/mL2), a lower median FPSA/TPSA (0.12) and a smaller median prostate volume (31.40 mL)

“ … We have developed a simple predictive model combining the SUVmax based on ⁶⁸Ga-PSMA PET/CT with traditional clinical risk factors, which can achieve a highly accurate and noninvasive diagnosis of (csPCa) in patients falling within the PSA gray zone,” added Dr. Yang and colleagues. “ … The combination of ⁶⁸Ga-PSMA PET/CT and PSA tests provides a good performance-efficiency-diagnostic model to improve the net benefit and reduce the number of unnecessary prostate biopsies.”¹

In regard to study limitations, the researchers acknowledged a relatively small sample size with the retrospective single-center study. The study authors also noted a lack of randomization with the study cohort and the use of multiple biopsy methods for pathological reference standards.

Reference

1. Yang J, Li J, Xiao L, Zhou M, Fang Z, Cai Y, Tang Y, Hu S. 68Ga-PSMA PET/CT-based multivariate model for highly accurate and noninvasive diagnosis of clinically significant prostate cancer in the PSA gray zone. Cancer Imaging. 2023;23(1):81. doi: 10.1186/s40644-023-00562-x