PD17-06\u2003MAPPING OF SITE-SPECIFIC RELAPSE IN PATIENTS WITH BIOCHEMICAL RECURRENCE FOLLOWING RADICAL PROSTATECTOMY ASSESSED BY 68GA-PSMA-11 OR 11C-CHOLINE PET/CT: IMPACT OF POSTOPERATIVE ANDROGEN DEPRIVATION THERAPY AND RADIOTHERAPY

Abstract

INTRODUCTION AND OBJECTIVES: Despite the curative intent of radical prostatectomy(RP) for localized prostate cancer, many patients experience biochemical recurrence(BCR). We report site-specific relapse patterns of post-prostatectomy patients with BCR assessed by 68Ga-PSMA-11 or 11C-Choline PET/CT and investigated the impact of postoperative androgen deprivation therapy(ADT) and radiotherapy(RT) on the anatomic distribution of relapse. METHODS: We identified 243 patients with BCR after RP with at least one positive lesion on 68Ga-PSMA-11 or 11C-Choline PET/CT between 2010 and 2017 at a single tertiary referral center. Positive lesions were mapped as local, nodal, skeletal or visceral recurrence (Table 1). Patients were categorized according to postoperative RT and ADT treatment in 3 subgroups (RT, ADT and RT+ADT) and compared with the reference group (no ADT or RT). Non-parametrical tests were used and overall patterns of relapse were described using frequencies and percentages. RESULTS: 192 (79%) patients were evaluated with 68Ga-PSMA-11 PET/CT and 51 (21%) with 11C-Choline PET/CT. Median PSA at the time of imaging was 1.4, 2.9, 1.9 and 1.1 ng/ml in the RT, ADT, RT+ADT and reference group, respectively (p=0.17). Patients in the ADT group had less nodal recurrence compared with the reference group (53.1%vs 79.4%; p=0.02). No statistically significant difference in skeletal recurrence was found between any subgroup and the reference group, although patients treated with ADT had a greater tendency towards having bone metastases. Patients in the reference group had no local relapse compared with 31.2% in the ADT group. CONCLUSIONS: The relapse pattern of post-prostatectomy patients with BCR is significantly affected by postoperative ADT and/or RT. Patients with BCR following RP or RP+RT have a relapse pattern which is predominantly nodal, mostly below the aortic bifurcation. Therefore, many of these patients are amenable for local salvage or metastasis-directed therapy. In contrast patients who develop BCR following RP+ADT or RP+RT+ADT more often have local, skeletal and extrapelvic nodal relapse and are therefore less likely to benefit from local salvage or metastasis-directed therapy. Table. No title available. Source of Funding: none