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The TA-P-OLIM Study (Percutaneous Thermo-Ablation of Prostate Cancer OligoMetastasis) is a prospective, interventional phase II study designed to evaluate the feasibility, efficacy, and safety of percutaneous thermal ablation (TA) as a metastasis-directed therapy (MDT) for patients with oligometastatic prostate cancer. So far, these metastases have been locally treated with stereotactic body radiation therapy (SBRT) or surgical resection.

Percutaneous TA is a minimally invasive technique that locally destroys tumor tissue using either heat (via microwave or radiofrequency ablation) or cold (via cryoablation). This is achieved by inserting specialized needles into the tumor through a small skin incision under image guidance.

TA offers a valuable treatment option for patients who are not suitable candidates for SBRT, such as those with prior radiation exposure or metastases located near critical anatomical structures. In many of these cases, ablation remains feasible through the use of adjunctive thermoprotection techniques, where fluid is injected via a needle to gently displace critical structures, thereby creating a safe buffer zone during treatment.

Preliminary retrospective evidence shows that TA achieves comparable local tumor control rates to SBRT/resection with minimal complications.7 As a minimally invasive procedure, TA typically requires only a brief hospital stay-often on an outpatient basis-and enables rapid recovery. This makes TA an attractive alternative to surgery, which is associated with greater morbidity, longer recovery times, and limited suitability for some patients. In contrast to SBRT, TA also allows for simultaneous tissue sampling which is completed in a single session. Moreover, it can be safely repeated in the event of local recurrence.

The study focuses on patient-centered endpoints such as local control and tolerability, aiming to improve quality of life through personalized, minimally invasive treatment strategies. TA also offers an effective local treatment option for patients who are not eligible for standard treatments such as SBRT. In this way, an alternative to both SBRT and surgery is provided, enabling continued local treatment for patients.

Patients are eligible if they have previously received radical treatment for prostate cancer (surgery or radiotherapy, with or without hormonal therapy), subsequently developed a limited number of metastases (1-5), and are no longer candidates for or deny SBRT.

UZ Ghent, with its long-standing research expertise in metastasis-directed therapies for oligometastatic prostate cancer, coordinates the study. The project was established in collaboration with various departments within the Urological Multidisciplinary Tumor Board. Several centers in East and West Flanders have already confirmed their willingness to participate in the study.

Inclusion criteria:

• > 18 years old
• PCa, treated with curative intent (radical prostatectomy, primary radiotherapy, or a combination of both) and oligorecurrent/oligopersistent metastasis (1 - 5 lesions) on imaging (PSMA-PET, CT, MRI).
• Recurrence or progression of metastases on imaging (PSMA-PET, CT, MRI) that cannot be treated with SBRT, either due to a history of previous high-dose radiotherapy with dose constraints, because SBRT is technically unfeasible or unsafe for the specific lesions, or because the patient refuses to undergo SBRT.
• PSMA-positive lesion
• Lesions up to 4 cm that are suitable and safe for TA with an anticipated high rate of technical success
• 'Eastern Cooperative Oncology Group' (ECOG) performance status of 2 or less.
• Patients can be androgen sensitive (mHSPC) or castration resistant (mCRPC).
• All patients will be discussed at the Multidisciplinary Tumor Board.

Exclusion criteria:

• <18y
• Severe comorbidity which limits the further life expectancy of the patient to < 2 years (opinion of the physician) and no malignancies < 2 years ago except for non-melanoma skin cancer and non-muscle invasive bladder cancer.
• No local radical treatment of the primary tumor was performed.
• Lack of compliance
• Absence of consent of the patient
• Location: intracranial

Patients with oligometastatic prostate cancer, characterized by 1-5 metastases who are no longer eligible for or refuse SBRT