This prospective observational study aims to evaluate the prognostic significance of early postoperative prostate-specific antigen (PSA) levels in patients undergoing radical prostatectomy for prostate cancer.

No investigational interventions will be performed. All diagnostic procedures, follow-up assessments, and treatments will be conducted in accordance with standard clinical practice and established prostate cancer management guidelines. Participation in the study will not influence treatment decisions.

This is a prospective, single-center, observational, investigator-initiated study designed to evaluate the prognostic significance of early postoperative prostate-specific antigen (PSA) levels in predicting long-term oncological outcomes after radical prostatectomy (RP) for prostate cancer.

The study does not involve investigational medicinal products. No experimental interventions will be applied. Patient management will follow standard clinical practice and established national and international prostate cancer treatment guidelines. Participation in the study will not influence treatment decisions.

Approximately 100 radical prostatectomies are performed annually at the study center. It is anticipated that 400-500 participants will be enrolled over a 5-year recruitment period. No formal sample size calculation was performed due to the observational nature of the study.

All patients who fulfill the eligibility criteria will be offered to participate in the study during their inpatient stay for the operation.

First PSA measurement will be done at 4-8 weeks after surgery, preferably at 1 month.

PSA persistence, defined as a serum PSA level ≥0.1 ng/mL 4-8 weeks after RP, will be assessed as a potential predictor of adverse oncological outcomes.

If the first PSA value after RP is ≥0.1 ng/mL, the second measurement will be taken 4 weeks later. The third one will be taken 8 weeks later. If PSA value during the first year increases to >0.2 ng/mL, Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography (PSMA PET/CT) will be organized. PSA measurements will be continued based on disease progression, further treatment, and treating physician's recommendations.

If the first PSA value after RP is <0.1 ng/mL or the second PSA value decreases from ≥0.1 ng/mL to <0.1 ng/mL, PSA measurements will be taken at 3, 6, 9, ir 12 months after surgery, twice a year during the second and third year after surgery, and yearly thereafter.

PSA measurement could be taken more often and at different intervals due to disease progression, treatment or if advised by the treating physician.

Participants will be followed for up to 10 years according to routine clinical practice. Follow-up visits will occur according to routine clinical practice. Data will be collected from medical records and routine clinical documentation and entered into an electronic database.

The study will evaluate the association between early postoperative PSA levels and biochemical recurrence, metastasis, metastasis-free survival, overall survival, and cancer-specific survival. A prognostic model incorporating persistent PSA and other prostate cancer characteristics will be made. Diagnostic accuracy of PSMA PET-CT on patients with persistent PSA will be evaluated.

Inclusion Criteria:

• Patient is an adult biological male.
• Patient has morphologically confirmed and untreated prostate cancer.
• Patient who will be treated with open, laparoscopic or robot-assisted laparoscopic radical prostatectomy.
• Patient is informed about this observational study and has signed the informed consent form.

Exclusion Criteria:

• Patient has radiologically of morphologically confirmed prostate cancer metastases before the operation.
• Patient received neoadjuvant prostate cancer treatment.
• Patient is set to receive adjuvant treatment.
• Patient has any contraindications for the operation.

Study participants are patients undergoing radical surgical treatment for histologically confirmed prostate cancer in Lithuanian University of Health Sciences Hospital Kaunas Clinics, Department of Urology.

IPD sharing is currently undecided. Decisions regarding data sharing will be made after study completion in accordance with institutional policies and applicable data protection regulations.