Clinical Usefulness of Prostate-specific Membrane Antigen-ligand Positron Emission Tomography/Computed Tomography for the Detection of Prostate Cancer Biochemical Recurrence after Primary Radiation Therapy in Patients with Prostate-specific Antigen Below the Phoenix Threshold: Systematic Review and Meta-analysis

AIMS

After primary radiotherapy, biochemical recurrence is defined according to the Phoenix criteria as a prostate-specific antigen (PSA) value >2 ng/ml relative to the nadir. Several studies have shown that prostate-specific membrane antigen (PSMA)-ligand positron emission tomography/computed tomography (PET/CT) can help in detecting recurrence in patients with low PSA values. This study aimed to assess the detection rate and patterns of PSMA-ligand PET/CT uptake in patients with suspected biochemical recurrence after primary radiotherapy and with PSA levels below the Phoenix threshold.

MATERIALS AND METHODS

The meta-analysis was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Articles providing data on patients with suspected prostate cancer recurrence after primary radiotherapy with a PSA value below the Phoenix threshold and who underwent PSMA-ligand PET/CT were included. Quality assessment was carried out using the Quality Assessment of Diagnostic Accuracy Studies-2 tool (QUADAS-2).

RESULTS

In total, five studies were included, recruiting 909 patients (202 with PSA ≤2 ng/ml). The PSMA-ligand detection rate in the patients with ≤2 ng/ml ranged from 66 to 83%. The most frequent source of PSMA-ligand PET/CT uptake was local recurrence, followed by lymph node metastasis and bone metastasis. PSMA-ligand PET/CT uptake due to local-only recurrence was more likely in patients with PSA ≤2 ng/ml compared with PSA > 2 ng/ml: risk ratio 0.72 (95% confidence interval 0.58-0.89), P = 0.003. No significant differences were observed in the detection of PSMA-ligand uptake in other areas. Limitations include a lack of biopsy confirmation, cohort reports with small sample sizes and a potentially high risk of bias.

CONCLUSION

A significant detection of PSMA-ligand-avid disease was observed in patients with PSA levels below the Phoenix threshold. There was a higher likelihood of detecting local-only uptake when the PSA value was ≤2 ng/ml. The findings suggest that a critical review of the Phoenix criteria may be warranted in the era of PSMA-ligand PET/CT and highlight the need for further prospective trials.

[Echo-guided transrectal biopsy. An analysis of the results in a series of 1900 patients]

OBJECTIVE

To compare the results of US-guided transrectal biopsy in 1,900 patients with the diagnostic yield of DRE, transrectal US, PSA, PSA density and free PSA/total PSA ratio and to describe our approach based on the results of the comparative study.

METHODS

Over the last two years 1,900 patients have undergone biopsy; 4 to 6 specimens were obtained randomly from both prostatic lobes and areas identified by transrectal US and/or DRE as being suspicious. All patients underwent transrectal US, DRE and determination of serum total PSA and PSA density. Free PSA and free PSA/total PSA ratio were determined in 128 patients with PSA 4-10 ng/ml. Seventy had a second biopsy, 8 a third and 3 had a fourth biopsy.

RESULTS

The overall diagnostic yield was 40%. Biopsy was positive in 27% of patients with PSA 4-10 ng/ml; of these, 64% showed a positive DRE, 21% showed a negative DRE and 13% were negative for both DRE and transrectal US. DRE was positive in 32% of patients with PSA greater than 10 ng/ml, 39% of those with PSA 10-20 ng/ml and 62% of those with PSA greater than 20 ng/ml; transrectal US was positive in 58% of patients with PSA 10-20 ng/ml and in 77% of those with PSA greater than 20 ng/ml. A high specificity was found for both DRE and transrectal US. In patients with PSA 4-10 ng/ml, PSA density at a cutoff of 0.15 ng/ml/cc showed a sensitivity of 81% and a specificity of 20%, respectively. A second biopsy was positive in 20% of patients with a persistently elevated PSA and the incidence of tumors theoretically of little importance was 13%.

CONCLUSIONS

Patients aged less than 70 years whose general condition permit aggressive treatment of prostate cancer should undergo US-guided transrectal biopsy if PSA is greater than 4 ng/ml, regardless of DRE and ultrasound findings. PSA less than 20 ng/ml, PSA density and free PSA/total PSA ratio must be considered for a second biopsy. Sextant biopsy appears to have a good diagnostic accuracy and does not require taking additional specimens or including the transitional zone in the first biopsy. Before classifying a tumor as being of little importance on the basis of the biopsy findings, another biopsy must be performed.