The goal of this study is to evaluate the safety and effectiveness of the Vanquish Water Vapor Ablation System ("Vanquish") in participants with Grade Group 3 (GG3) intermediate-risk prostate cancer.

Participants will undergo therapy with the Vanquish System and complete follow up visits at 7 days, 6 weeks, 6 months, 12 months, 18 months, and 24 months.

Inclusion Criteria:

• Participant has been diagnosed with Grade Group 3 (GG3) intermediate risk prostate cancer.

• ≤20 ng/ml PSA.

• PSA density ≤0.15

• ≥50 years of age; with life expectancy of ≥10 years.

• Clinical cancer stage less than or equal to T2c (tumor may involve both sides of the prostate but without evidence that tumor extends outside of the prostate and with no cancer cells found in nearby lymph nodes) evaluated by PSMA PET scan.

• Within 6 months prior to signing consent have had a multiparametric MRI.

  1. mpMRI results must show localized disease meaning a single MRI region of suspicion (PI-RADS ≥3 with lesion volume ≤1.5 cc).
  2. Maximum lesion diameter in any MRI dimension must be ≤11.9 mm.

• Within 6 months prior to signing consent, have undergone a multiparametric MRI software guided fusion biopsy of the prostate (transrectal or transperineal)

  1. Central Pathology confirmation showing a minimum of 2 cores in aggregate of pattern 4 disease (GG3) in the targeted lesion identified by Central Imaging
  2. GG1 cores from anywhere in the prostate are acceptable
  3. Less than 50% of systematic biopsy cores are positive for GGG 1 or 2 disease. For the <50% calculation, all systematic positive cores located in the sector(s) containing the target, or in sectors immediately adjacent to the qualifying target, are counted as "one core."

• Within 6 months prior to signing consent have had a PSMA-PET scan.

  1. PSMA-PET results show no suspicion of metastasis as determined by site read
  2. Per Radiology Central Imaging, PSMA-PET scan prostate results are concordant with mpMRI results
  3. If PSMA indicates a hotspot separate from the lesion or planned treatment area, a targeted repeat biopsy is required to rule out ≥ GG2

• All positive GG2 or GG3 cores must be located in the lesion, or immediately adjacent to the lesion, as determined by pathology report and, if available, the fusion system's tracking, mapping and imaging documentation features.

• Participant is willing and able to adhere to specific protocol visits and required testing throughout study.

• Participant is geographically stable and near the site or able and willing to travel back to site for follow-up visits.

• Participant is able and willing to provide written consent to participate in the study.

• Participant is willing and able to receive ablative therapy within 90 days after signing consent.

Exclusion Criteria:

• Participants with ≥GG4 cores anywhere in the prostate.

• Participants with GG2 or GG3 cores outside the region of interest.

• Contraindications per the Vanquish Instructions For Use.

• Any previous treatment for prostate cancer or any prior surgery, intervention, or minimally invasive therapy (MIST) for the prostate or bladder neck, including but not limited to Vanquish therapy, TUIP, TURP, Aquablation, Green Light, Rezūm, Prostatic Urethral Lift, iTind, Prostatic Arterial Embolization, or microwave therapy.

• Currently taking medications that have hormonal effects on the prostate or PSA, such as:

  1. 5 alpha reductase inhibitors, if on for < 6 months (6-month washout required if participant is able and willing to stop medication)
  2. Androgen blockers,
  3. Luteinizing hormone-releasing hormone (LHRH) agonists or antagonists within the past 12 months,
  4. or Testosterone supplementation (3-month washout required) A participant on BPH medication which does not affect the PSA can be included.

• Treated within the past 5 years for a lower and/or upper urinary tract malignancy.

• Any cognitive or psychiatric condition that interferes with or precludes direct and accurate communication with the study Investigator regarding the study or affects the ability to complete the study quality of life questionnaires.

• Participant currently participating in other prostate tissue and/or cancer study unless approved by Sponsor in writing.

• Participant is considered vulnerable such as incarcerated or cognitively impaired.