EURURO Vol. 72 No. 3

Introduction

Energy-based partial gland ablation is an emerging

treatment for localized intermediate-risk prostate cancer

(PCa) that aims to reduce the morbidity associated with

radical whole-gland therapy while delivering cancer control

[1,2]

. These focal therapies are adapted to PCa location, such

as the peripheral zone (PZ), transition zone (TZ), or anterior

fibromuscular stroma (AFMS)

[3] .

Use of magnetic resonance imaging (MRI) and targeted

biopsies has led to better detection and localization of PCa,

such as diagnosing anterior prostate cancers (APCs)

originating from the TZ. APCs account for 19% of new

cancers

[4–7]

. We demonstrated that APCs originate from

the anterior and medial TZ as well as anterior to the urethra

in the midline

[8,9]

. Probably due to benign prostatic

hyperplasia (BPH), some APCs spread anteriorly into the

AFMS; then the anterior limit of the TZ acts as a barrier to

APCs extending posteriorly

[4]

An APC nodule can occasionally be located mainly within

the AFMS and anterior to the TZ boundary without any

cancer in the PZ. In these highly selected cases, which

represent 3–5% of new cancers (Supplement 1), focal or

partial treatment is appealing. However, delivering thermal

energy to an apical APC may be undesirable

[3]

, for fear of

compromising the external sphincteric unit and/or the

neurovascular bundles.

In this specific circumstance, we believe that en bloc

surgical excision of the anterior prostate (ie, TZ, AFMS,

anterior part of the PZ) would preserve intact the

posterolateral aspect of the distal (submontanal) urethra,

PZ, and periprostatic tissues. Doing so would effectively

ablate the tumor with a safety margin of benign tissue

posteriorly, deliver superior continence/potency outcomes

versus radical prostatectomy (RP), and allow pathologic

assessment of excised tissue. PSA nadir would still

potentially be an accurate marker for oncologic control,

and a complementary RP or ablative therapy could be

performed in case of cancer recurrence, with oncologic and

functional outcomes similar to RP.

The objective of our study was to evaluate the feasibility

and oncologic and functional outcomes of robot-assisted

anterior partial prostatectomy (APP) for isolated MRI-

detected APC in a highly selected cohort.

Patients and methods

2.1.

Study population

This study used a prospective single-arm single-center stage 2a

Innovation, Development, Exploration, Assessment, Long-term (IDEAL)

paradigm

[10]

. The robot-assisted APP technique innovation was carried

out by a few surgeons, deemed to be probably safe after the first five

cases, and was tested more broadly, although still experimental, in well-

selected patients. The intervention needed to be refined. A regulatory

process was required at this stage, and the study was approved by the

institutional review board at the University of Lille, France, where all

cases were treated. After detailed information was given to the patients,

written signed consent was obtained. Assessing safety for the first five

cases was based on bleeding (no transfusion), functional results at 6 mo

(International Continence Society [ICS] score 4), and oncologic results

(at least two of three cases with negative lateral/posterior margins).

After five consecutive surgeries in an 18-mo period, the investigators

decided to pursue the study. The decision to analyze the results after

17 patients was established empirically (median follow-up

24 mo was

reached).

Inclusion criteria comprised a multiparametric MRI (mpMRI)–

identified, predominantly anteriorly located tumor. It was proven at

targeted biopsy (two cores per lesion) and determined to be at low or

intermediate risk

[11,12]

. Cancer could be of any volume at MRI,

provided its posterior limits were at least 17 mm (posterior biopsy core

length) anterior to the rectal surface of the gland that defines the anterior

location of cancers, and its lateral limits were within the TZ or AFMS. The

whole prostate gland could be of any volume

[13]

. Exclusion criteria

were if the posterior aspect of the APC at MRI was located

5 mm

anterior to a coronal plane located at the level of the posterior TZ

boundary

( Fig. 1 )

or MRI-targeted biopsies Gleason score (GS)

7, an

anterior bulging of the tumor beyond prostate boundaries or extension

in the preprostatic fat or bladder neck (BN), a cancer length

3 mm at

12 systematic posterior biopsies in an adjacent sector to the anterior

cancer, or an additional clinically significant PZ cancer (

3 mm of cancer

on one core at 12 systematic posterior biopsies or at MRI-targeted

biopsies to an secondary posteriorly located lesion at MRI). Patients who

refused to consent were offered RP, radiation therapy, and/or active

surveillance. Over an 8-yr period (January 2008 to December 2015),

28 patients fulfilled the entry criteria, of whom 17 (60%) gave informed

consent and were enrolled in the study.

All patients underwent prebiopsy mpMRI, followed by MR-targeted

biopsies to any visible lesion, plus a 12-core systematic transrectal

ultrasound–guided biopsy. Self-administered validated quality-of-life

(QOL) questionnaires were used to assess preoperative urinary function

(International Prostate Symptom Score [IPSS]), continence (ICS: 1–2),

and potency (International Index of Erectile Function [IIEF]-5). Potency

was defined as an IIEF-5 score 20 with or without drugs. Preoperative

mpMRI protocol was performed within 3 mo of surgery and included

axial (and sagittal, if necessary) gadolinium-enhanced sequences to

assess the contour and the craniocaudal extent of the biopsy-proven

cancerous area

[8]

2.2.

Surgical technique

Robotic surgery consisted of en bloc excision of the anterior part of the

prostate composed of the AFMS, BN, prostate adenoma (TZ and median

lobe) along with the proximal prostate urethra, PZ apical anterior horns,

anterior aspect of the distal (submontanal) urethra, and anterior BN

(Supplement 1, Fig. 1). Only three cases had lymph node dissection due

to suspicious enlarged pelvic node enlargement at MRI (

= 2) and GS 4 +

3 (

= 1).

Perioperative data including peri- and postoperative treatment-

related adverse events, and time to bladder catheter removal were

recorded. Cancer location, volume, and margins were assessed according

to the Stanford technique

[14]

. We differentiated positive posterior

surgical margins at the posterior aspect of the excised specimen from

anterior surgical margins that are an artifact occurring when prepro-

static fat is removed during exposure in patients with APC. Patients with

a positive posterior margin underwent mpMRI and biopsy of the PZ

within 3 mo after surgery. We recommended that patients with a

positive biopsy have a robot-assisted salvage nerve-sparing RP

(Supplement 1).

All patients underwent PSA monitoring at 3 and 6 mo and then every

6 mo and had mpMRI at 6–12 mo. At 6 mo, protocol-based 12-core and/

or targeted biopsies were performed in the first seven patients. Because

biopsies were negative when MRI was not suspicious, only for-cause

biopsies were performed in the remaining 10 patients. Self-administered

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