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Objective:
MRI-guided transurethral ultrasound ablation (TULSA) of the prostate uses ultrasound to thermally coagulate tissue in-bore. Treatment parameters are automatically controlled in real-time by matching feedback from MRI thermometry to the ablative energy administered to the prescribed volume. The TACT pivotal study of TULSA established primary safety and efficacy at 1 year. Here we report the 5-year follow up from the TACT study.

Materials and Methods:
There were 115 men with localized prostate cancer (PCa) were enrolled across 13 sites in five countries. Eligibility included grade group (GG) 1-2 disease, stage = T2b, and PSA = 15 ng/mL. Men received a single, whole-gland TULSA treatment, sparing the prostatic urethra and urinary sphincter. Primary endpoints at 1 y were PSA reduction and adverse events. Secondary endpoints at 1 y included recurrence on 10-core biopsy and mpMRI, and prostate volume reduction on mpMRI. Adverse events, quality of life questionnaire, PSA, and the rate of salvage treatment were assessed to 5 y.

Results:
At baseline, (median [IQR]) age and PSA were 65 (59 - 69) years and 6.3 (4.6 - 7.9) ng/mL. Median prostate volume on central radiology review decreased from 37.3 mL to 2.8 mL by 1 y after treatment (92% decrease). At baseline and 1 y, 72/115 (63%) and 17/111 (15%) had GG2 disease. By 5 y, median (IQR) PSA decreased to 0.63 (0.18 - 1.9) ng/mL (<em>n</em> = 68). Twenty-five men (22%) received salvage treatment, without unexpected complications (10 prostatectomy, 11 radiotherapy, three radiation plus ADT, one surgery plus radiation). Early predictors of treatment failure by 5 y included 1 y PSA (OR = 3; CI [1.7, 5.4]) and positive 1 y mpMRI (OR = 12; CI [4.4, 34]) (both <em>p</em> = 0.001). On failure analysis, preventable errors in patient selection or targeting, or misalignment due to intraprocedural swelling/motion were identified. By 5 y, 61/66 (92%) recovered pad-free continence; 80/92 (87%) preserved erections sufficient for penetration. Grade 3 adverse events occurred in 12 men (10%), with no Grade 4 event or rectal injury.

Conclusion:
By 5 y after a single, whole-gland TULSA procedure, 78% of men had effective disease control. Favorable safety and functional outcomes were also durable to 5 y. Subsequent protocol modifications, such as excluding patients with intraprostatic calcifications that can lead to undertreatment, modern strategies for device positioning, and thermal dose escalation to address undertreatment visible on intraprocedural imaging, may improve rates of local control. Intraprocedural imaging parameters, positive MRI and rising PSA at 1 y predicted salvage therapy by 5 y. Overall, the results demonstrate a less invasive treatment option for patients with localized prostate cancer with durable safety and efficacy. A randomized controlled trial comparing TULSA with radical prostatectomy is underway (NCT05027477).