Presurgical [68Ga]-Ga-PSMA-11 Positron Emission Tomography as a surrogate of pelvic lymph node dissection for biochemical recurrence risk assessment

Abstract

Purpose

To compare the prognostic value for biochemical recurrence (BCR) free-survival (FS) of a CAPRA-S score (Cancer of the Prostate Risk Assessment) calculated replacing pelvic lymph node dissection (PLND) information with pre-operative PSMA PET findings (CAPRA-S-PSMA).

Methods

This is a follow-up study of the surgery cohort included in the multicenter prospective phase 3 imaging trial (n = 277; NCT03368547, NCT02611882, NCT02919111). Local histopathology score (CAPRA-S score without PLND), PSMA-PET N1/M1, and pN1 were used to assess risk of BCR. Patients were followed up after RP by the local investigators using electronic medical records. BCR was defined by a prostate-specific antigen (PSA) level ≥ 0.2 ng/mL after RP or an initiation of PCa specific secondary treatment (> 6 months after surgery). Univariate, multivariate Cox model, and c-statistic index were performed to assess the prognostic value of PSMA-PET, pN1 and its added value to local histopathology risk score.

Results

From December 2015 to 2019, 277 patients underwent surgery after PSMA-PET. Clinical follow-up was obtained in 240/277 (87%) patients. PSMA-PET N1/M1 and pN1 were found in 41/240 (17%) and 67/240 (28%) patients respectively. Median follow-up from surgery was 32.4 (IQR 23.3–42.9) months. 91/240 BCR events (38%) were observed. Only local histopathology score and PSMA PET were significant in multivariate analysis for BCR-FS (HR [95%CI]: 1.4 [1.2–1.5] P < 0.0001) and (1.7 [1–2.9] P = 0.03). Prognostic value of model CAPRA-S-PSMA was not significantly different than model CAPRA-S-PLND (c-statistic 0.74 [0.69–0.79] vs. 0.73 [0.68–0.78]; P = 0.69).

Conclusion

Switching PLND information by pre-surgical PSMA PET extra prostatic findings in the reference CAPRA-S score showed no significant difference in predicting BCR-FS in patients with intermediate-risk to high-risk PCa.