Analysis of the Performance of PSMA Emission Tomography in Patients With Prostate Cancer Treated With HIFU

The management of localised prostate cancer (PaC) in men with favourable risk factors is contentious, often involving whole prostate treatment due to its multifocal nature in 40% of cases. Active surveillance (AS) is increasingly used to mitigate overtreatment risks in well-selected patients, supported by long-term data from large cohorts. Focal therapy is emerging as an alternative, aiming for effective cancer control while minimizing morbidity, with radical treatment available for relapse. High-intensity focused ultrasound (HIFU) shows promise for focal therapy, supported by the HIFI-1 study and the HAS report (November 2023), indicating its non-inferiority to radical prostatectomy in controlling intermediate-risk disease with less morbidity.PSMA PET imaging aids in diagnosing and assessing prostate cancer risk at diagnosis and after treatment, guiding management decisions. However, ultrasound artefacts can hinder MRI interpretation post-HIFU treatment. PSMA PET, particularly using PRIMARY score and PROMISE V2 criteria, helps in assessing disease extent, akin to miTNM classification based on cancer location and spread on molecular imaging. Overall, integrating these technologies and criteria improves the precision of prostate cancer diagnosis, risk estimation, and treatment planning The aim of this study is to evaluate the effectiveness of positron emission tomography (PSMA PET) compared with MRI in detecting clinically significant recurrence of prostate cancer (PaC) after treatment with HIFU. The aim is to measure the sensitivity and specificity of these two imaging modalities one year after treatment, with a view to improving the post-treatment follow-up strategy for PaC Patients with low intermediate risk prostate cancer with specific criteria (HAS 2023) will be included in the study. Pre-operative nuclear imaging will be performed in addition to routine diagnostic tests. Routine follow-up at 6 months will include a digital rectal examination (DRE) and PSA and Phi index measurements. At 1 year, in addition to routine follow-up (DRE, PSA, Phi index, MRI and prostate biopsy), patients will undergo a PSMA PET scan.

Inclusion criteria

• Patient with prostate cancer
• Age ≥ 70 years (HAS 2023)
• Life expectancy > 5 years
• Clinical stage Clinical stage T1c - T2a PSA < 20 ng/ml Biopsy :ISUP 2 unilateral on a maximum of 2 contiguous sextants with or without ipsilateral or contralateral focus ISUP1 single focus or multiple foci if only one ISUP 2 focus on targeted biopsy
• Imaging Single lesion PIRADS 3 or 4 or 5 Volume of prostate gland < 150 ml
• Enrolled in a social security scheme
• Signature of consent

Exclusion criteria

• Evidence of extra-prostatic extension or invasion of the seminal vesicles.
• Any condition that, in the judgement of the investigators, would interfere with the subject's ability to
• provide informed consent, comply with study instructions, expose the subject to increased risk, or interfere with the interpretation of study results.
• Patients deprived of their liberty or under legal protection (curatorship and guardianship, safeguard of justice)
• Hypersensitivity to the active substances or to any of the excipients
• Conditions contraindicating magnetic resonance imaging (MRI), such as the presence of internal metallic devices.
• Chronic kidney disease with an eGFR ≤ 60 mL/min
• Liver failure