Do we need to redefine the Phoenix criteria after the arrival of the new generation imaging techniques?

person Rodrigo Muelas Radiation Oncology Department, Hospital Provincial de Castellón, Castellón, Spain info_outline Rodrigo Muelas, Clara Puerto Francés, Virginia Morillo, Angel L. Sanchez, Teresa Piquer, Encarnación Fernández Camacho, Vanessa Aznar-Tortonda, Patricia Plaza, Maria Mingarro de leon, Carlos Ferrer-Albiach

Authors person Rodrigo Muelas Radiation Oncology Department, Hospital Provincial de Castellón, Castellón, Spain info_outline Rodrigo Muelas, Clara Puerto Francés, Virginia Morillo, Angel L. Sanchez, Teresa Piquer, Encarnación Fernández Camacho, Vanessa Aznar-Tortonda, Patricia Plaza, Maria Mingarro de leon, Carlos Ferrer-Albiach Organizations Radiation Oncology Department, Hospital Provincial de Castellón, Castellón, Spain, Consorcio H. Prov. Castellon, Castellón De La Plan, Spain, Radiotherapy, Hospital Provincial de Castellón, Castellón De La Plana, Spain, Consorcio hospitalario provincial Castellon, Castellón De La Plana, Spain, Hospital Provincial de Castellon, Castello De La Plana, Spain, Consorcio H. Prov. Castellon, Castellón, Spain Abstract Disclosures Research Funding No funding received None. Background: The biochemical recurrence (BCR) criteria are different depending on the primary tumour treatment: PSA ≥0.2 ng/mL after radical prostatectomy (RP) and PSA ≥ 2 ng/mL above the nadir after radiotherapy (RT)[Phoenix criteria]. The latter was established based on the detection of metastasis by conventional imaging tests (CT and bone scanning). Next generation imaging (NGI) techniques ( 18 F-choline PET/CT and specially 18 F-PSMA PET/CT), allow detection of metastasis with PSA values much lower than the Phoenix criteria. The purpose of this study is to compare the profile of patients diagnosed with metastatic hormone sensitive prostate cancer (mHSPC) by NGI techniques after BCR according to the primary tumour treatment performed. Methods: Patients diagnosed with mHSPC in our Radiation Oncology Department after BCR between February 2021 and December 2022 were reviewed. All of them underwent NGI: 18 F-choline PET/CT if there was BCR following RT or a PSA level > 2 ng/ml after PTR; 18 F-PSMA PET/CT if there was BCR after PTR or if 18 F-choline PET/CT offered diagnostic uncertainties. Then, were stratified according to primary treatment: PTR (+/- salvage RT to the prostatic bed) vs RT (external or brachytherapy). PSA levels prior to NGI, number of metastases (≤5: oligometastatic vs > 5: polymetastatic) and their location (M1a: exclusive lymph node metastasis, M1b: presence of bone metastasis and M1c: presence of visceral metastasis) were compared. Results: A total of 38 patients were idiagnosed with mHSPC: 42.1% after PTR and 57.9% after RT. PTR group had PSA levels prior to NGI of 1.08 ng/ml, of which 75% were 18 F-PSMA PET/CT. Twenty-five per cent of patients in this group were classified as polymetastatic. In RT group the median PSA levels prior to NGI was 3.5 ng/ml, of which 68.2% were 18 F-choline PET/CT. The proportion of polymetastatic patients was 50%. The location of metastases in PTR and RT group was: M1a (68.8% vs 59.1%), M1b (31.3% vs 36.4%) and M1c (0% vs 4.5%). Conclusions: The percentage of polymetastatic patients in RT group is double that of PTR group, which is a worse prognostic factor. (4). This difference in the number of metastases is due to the higher PSA levels prior to NGI in RT group, which is directly related to the definition established by the Phoenix criteria(3). Given that NGI techniques can detect metastases with PSA values below the Phoenix criteria, it would be reasonable to redefine it in order to reduce the percentage of polymetastatic patients through earlier detection and thus improve their prognosis.