Abstract: PD61-02
Sources of Funding: none

Introduction

With current standard cross-sectional imaging (CT or MRI) detection of prostate cancer lesions in patients with biochemical recurrence (BCR) after radical prostatectomy remains challenging, especially at low PSA values. Recently, 68Ga-PSMA PET imaging has been shown to improve detection rates. However, up to now published case series include only a limited number of patients at low PSA values.

Methods

For this retrospective analysis 272 pts with BCR after radical prostatectomy were extracted from the institutional database who presented with a PSA value from 0.2 up to 1ng/ml at the time of 68Ga-PSMA PET/CT imaging. 68Ga-PSMA PET/CT was evaluated by one experienced reader for lesions suggestive for prostate cancer recurrence and site of suspicious lesions was reported. Patients were grouped according to PSA value, from 0.2 – 0.5ng/mL and from >0.5 – 1.0ng/mL. Primary T-, N-stage, Gleason-Score, D´Amico-Classification, previous local radiation therapy as well as concurrent androgen deprivation therapy (ADT) was correlated to detection rates.

Results

In total, in 54.5 % (73/134) of patients with PSA from 0.2 – 0.5ng/mL and in 76.1% (102/134) of patients with PSA >0.5 – 1.0ng/mL suspicious findings on 68Ga-PSMA PET/CT imaging were noted. Sites of recurrence were local (37.0% and 41.2%), pelvic or retroperitoneal lymph nodes (45.2% and 54.9%), bone (24.7% and 29.4%), supradiaphragmal lymph nodes (6.8% and 6.9%) as well as others (4.1% and 2.0%). In patients with primary locally advanced tumors (pT>3a), primary N+ disease, Gleason-Scores >8, primary higher D´Amico-Classification, previous radiation therapy as well as with concurrent ADT positive findings on 68Ga-PSMA PET/CT were more likely compared to patients without these characteristics.

Conclusions

68Ga-PSMA PET/CT is able to identify sites of recurrent prostate cancer after radical prostatectomy even at low PSA values up to 1ng/ml in a significant number of patients – especially in patients with primary more aggressive tumor characteristics, previous local radiation therapy or concurrent ADT – and thus will very likely present the future imaging technique in these patients. As salvage therapies (local radiation therapy, salvage lymph node dissection or PSMA-radioguided surgery) are most effective at low PSA-levels, early detection of cancerous foci by 68Ga-PSMA PET might even improve oncological results.

Funding

none