Role of transrectal ultrasonography in the follow-up of patients treated with prostatic cryosurgery.

Cryosurgery of prostate is a minimally invasive treatment for localized cancer. Imaging techniques (transrectal ultrasound (TRUS) or magnetic resonance) have been proposed to evaluate tumor persistence/recurrence after cryosurgical treatment other than serum PSA and prostate biopsies. Actually, criteria to identify cancer after cryosurgical ablation are not well assessed. Aim of this study is to evaluate the clinical significance and role of TRUS in detecting tumor within the former prostate gland after cryoablation. We evaluated ultrasound (US) features and imaging, serum PSA and biopsies in 20 patients treated by cryosurgery at our Hospital with a mean follow-up of 18 months. Twenty patients (mean age 70 years, PSA 25.9 ng/ml, clinical stage: 10 T2 N0M0 and 10 T3 N0M0) were followed up for a mean of 16 months. Ultrasound findings (gland volume, capsule, hypoechoic area, post-voided urine volume, seminal vesicles) were correlated to PSA levels (every 3 months) and prostate biopsies (6, 12 and 24 months). All cases were evaluated by the same ultrasound scanner (Eidos, Hitachi-5-6.5 MHz) and by two operators. Prostate capsule was interrupted by hypo-hyperechoic areas in all cases. Transition zone was no more recognizable. Ultrasound findings showed in all cases hypoechoic areas, but US did not identified tumor recurrence in 2 patients. During follow-up, PSA below 0.5 ng/ml was recorded in 75% of cases. We detected tumor in 2 cases, respectively 12 and 18 months after cryosurgery: in the first case few residual cancer cells within fibrous tissue were found in 1 out of 6 biopsies at 6 months (PSA 0.58 ng/ml), in the second one, tumor with viable normal prostatic glands was found in one biopsy of the apex at 18 months (PSA 4.0 ng/ml). TRUS showed several anaechoic foci with necrotic tissue and coalescence of liquid areas in 2 patients (one developed acute urinary retention). Actually, serum PSA is the best marker in order to detect clinically significant tumor after cryosurgery. Hypoechoic areas and capsule interruptions observed by ultrasound imaging of prostate gland after cryosurgery are not correlated with tumor recurrence or tumor persistence. TRUS is only indicated for ultrasound-guided biopsies during follow-up and to confirm urologic complications.