With the increasing use of prostate MRI, focal therapy for prostate cancer (PCa) has become an emerging treatment option for select patients.¹ Although consensus guidelines are lacking,² focal therapy is considered an option for patients with MRI-concordant, unifocal, low or intermediate risk PCa who are unwilling to pursue active surveillance or radical treatment. Focal therapy candidates may be limited,³ but for these patients the improved functional outcomes associated with focal therapy are important: 92% to 100% pad-free rates and minimal/no erectile dysfunction (ED) at 12 months depending on the energy source used.^1,4 While high-intensity focused ultrasound (HIFU) is delivered transrectally and transurethrally, other focal therapy energy sources are delivered percutaneously from a transperineal approach, such as irreversible electroporation, cryotherapy, photodynamic therapy, and laser ablation. Thus, anterior midline tumors are challenging to treat as (1) HIFU is often less effective for anterior tumors, and (2) the risk of injury to the urethra and sphincter limits transperineal access to this region.⁴ For these reasons, we performed robot-assisted partial prostatectomy (RAPP) as a form of focal therapy for a patient with an anterior midline tumor in 2020.

Partial prostatectomy was described in 2017 by Villers et al,⁵ who reported 17 partial prostatectomies for low- and intermediate-risk PCa. Similar to ablative focal therapy approaches, the functional outcomes were excellent with no incontinence reported and ED noted in only 12% of patients at 6 to 12 months follow-up. Importantly, recurrence-free survival was 86% at 2-year follow-up. In 2021, Sood et al⁶ described a “precision prostatectomy” in 88 patients, which included excision of the dominant PCa lesion and most of the surrounding ipsilateral tissue (analogous to a hemi-ablation). They also reported excellent functional outcomes with 91% pad-free rates and ED noted in only 10.2% of patients at 12 months. Recurrence-free survival was 93% at 3-year follow-up.

Since offering RAPP as a focal therapy option in 2020, we have performed 7 cases as described henceforth.⁷ We selected patients with low- or intermediate-risk PCa that was isolated to an anterior MRI-concordant lesion who had opted for focal therapy. Representative MRI images of 3 patients are provided in Figure 1. None of our patients had baseline urinary incontinence or ED. RAPP was performed with the patient in dorsal lithotomy position. Each case began with transrectal ultrasound and transperineal percutaneous placement of three to five 22-gauge spinal needles to demarcate the posterior, proximal, and distal boundaries of the tumor. In some cases, MRI-fusion was used with UroNav (Philips, Andover, Massachusetts), while ExactVu micro-ultrasound (Exact Imaging, Markham, Ontario) was used in others. The DK technologies stepper-stabilizer system (DK North America, Atlanta, Georgia) was used, such that real-time transrectal ultrasound of the prostate could be performed by an assistant and viewed by the surgeon in the robotic console via the TilePro function (Intuitive, Sunnyvale, California). Standard transperitoneal robotic access was obtained, the space of Retzius was developed, the endopelvic fascia was opened, and the dorsal venous complex was partially or completely ligated. Representative intraoperative images are provided in Figure 2. Using a combination of the previously placed spinal needles as boundary guides and the real-time transrectal ultrasound, the tumor was excised from the prostate similar to an off-clamp robotic partial nephrectomy of an endophytic tumor.⁸ After excision and inspection of the specimen, an additional deep margin(s) was sent separately. In 6/7 = 86% of cases, the urinary tract was not entered, and extraprostatic fat was sutured into the partial prostatectomy defect, with the catheter removed on postoperative day 1. In one case, the anterior prostatic urethra was entered during dissection and was closed with an inverted Y-V plasty approach similar to that used for bladder neck contractures.⁹ The catheter remained in place for 7 days and was removed after cystogram revealed no leak.

Pre- and postoperative characteristics are provided in the Table. The mean patient age was 72.6 years, the mean preoperative PSA was 7.9 ng/mL, and the mean lesion size was 1.9 mL. All patients had MRI-concordant PCa with targeted biopsies revealing Gleason 4 + 3 = 7 in 2 cases, Gleason 3 + 4 = 7 in 4 cases, and Gleason 6 in 1 case (for which Decipher genomic classifier was 0.54). Final pathology demonstrated Gleason 4 + 5 = 9 in 2 cases, Gleason 4 + 3 = 7 in 1 case, and Gleason 3 + 4 = 7 in 4 cases. Notably, upgrading occurred in 4/7 = 57.1% of cases. Excised specimen margins were positive in 4 cases, 2 of which had an additional deep margin that was negative. Postoperatively, patients were followed with PSA every 3 months, prostate MRI every 6 months, and repeat biopsy was recommended every 12 months. In all cases, there were no changes reported from baseline urinary and sexual function. There were no intra- or postoperative complications. At a mean follow-up of 26.4 months, 8/9 = 88.9% of patients have had no subsequent treatment and no Gleason 7+ recurrences. One patient opted for standard of care radiation with androgen deprivation therapy due to upgrading to Gleason 4 + 5 = 9 on RAPP pathology. Excluding this patient, the mean postoperative PSA at the most recent follow-up was 1.44 ng/mL, which represents a 77.4% reduction from the mean preoperative PSA.

Table. Pre- and Postoperative Characteristics for Patients Who Underwent Robot-Assisted Partial Prostatectomy

For carefully selected patients with PCa who desire focal therapy to preserve urinary and sexual function, and who understand the oncologic trade-offs associated with potentially delaying radical therapy, RAPP is a technically feasible option for MRI-concordant isolated anterior PCa. As noted in our series, the advantage of RAPP over ablative options is the availability of PCa tissue for final pathology confirmation. Despite prebiopsy MRI and a transperineal approach to prostate biopsy, upgrading occurred in most of our cases, which has significant clinical implications. For example, the recommended androgen deprivation therapy duration for our most recent patient most likely would be different based on his biopsy pathology (Gleason 4 + 3 = 7) vs his RAPP final pathology (Gleason 4 + 5 = 9). While more patients and longer follow-up are needed, RAPP should be considered in the armamentarium of focal therapy options, particularly for patients with anterior midline tumors that are challenging to access via transperineal percutaneous ablation and can be difficult to treat effectively with HIFU.