Denonvilliers fascia as described by Cuneo and Veau in 1899 [1] results from the fusion of the peritoneal walls of the rectovesical pouch during embryonal development. In the adult it is a single layer of tissue that separates the prostate from the rectum and only with electronic microscopy is it possible to distinguish a two-layer quality. Strictly speaking, it is impossible to differentiate between an anterior layer and a posterior layer of Denonvilliers fascia. However, there is controversy in the literature and some authors, such as Villiers et al. [2], state that the connective tissue or thin fascia that surrounds the seminal vesicles is part of the anterior layer of Denonvilliers fascia.

The controversy in the anatomic nomenclature does not stop here. Evolution of the laparoscopic radical prostatectomy technique during recent years has brought new concepts and further controversies. Most laparoscopic surgeons describe three different types of dissection: the intrafascial, the interfascial, and the extrafascial. It is not clear, however, if all authors mean the same when they speak about a given plane of dissection.

Martínez-Piñeiro et al. in a recent publication [3] follow the original description of Cuneo and Veau [1]. They only recognize a single layer of Denonvilliers fascia that separates the anterior rectal wall from the posterior aspect of the prostate, covered by the prostatic fascia. Denonvilliers fascia, following their description, is attached to the prostatic base and most caudal aspect of the seminal vesicles and vasa deferentia (Fig. 1). Entering the interfascial plane would require either the section of these adhesions or a double cutting of Denonvilliers fascia at this point (Fig. 2). Furthermore, Martínez-Piñeiro et al. [3] describe an anterior extension of Denonvilliers fascia that covers the medial aspect of the neurovascular bundles. For these authors, the interfascial plane would be an avascular plane between the prostatic fascia and Denonvilliers fascia posteriorly and between the prostatic fascia and the anterior extension of Denonvilliers fascia at the posterolateral aspect of the prostate (Fig. 3). The intrafascial plane would run under the prostatic fascia. Therefore, for these authors complete preservation of the neurovascular bundles is possible either with the intrafascial or interfascial dissection technique (Fig. 3).

Fig. 1. Sagittal view of prostatic fascial anatomy [3].

Fig. 2. Entering the interfascial plane requires either the section of the adhesions of Denonvilliers fascia to the prostatic base or a double cutting of Denonvilliers fascia at this point [3].

To avoid confusion, urologists should find a consensus in the nomenclature about the fascial anatomy of the prostate and the different surgical anatomic planes that can be followed during laparoscopic radical prostatectomy.

Regardless of the nomenclature controversies, the report by Secin et al. [4] is a good example of showing that patient selection can bias the percentage of positive surgical margins and that complete neurovascular bundle preservation is possible with a low positive margin rate. They had more positive surgical margins with interfascial dissection than with intrafascial dissection, which theoretically leaves no connective tissue around the prostate. These results can only be explained by the fact that patients with higher preoperative risk factors were selected for the so-called interfascial dissection and low-risk patients mainly for the intrafascial approach.

Patient selection for neurovascular bundle preservation can be done by using published nomograms that estimate the risk of extracapsular extension [6], [7], [8] or with the judicious use of prostatic biopsy information (percent of tumour in the biopsy cores, biopsy Gleason score, number of biopsy cores with tumour) as demonstrated by Secin et al. [4] . The combination of prostate-specific antigen (PSA) density and biopsy Gleason score can also be of great help. Martínez-Piñeiro et al. [5] in a series of 600 patients showed that positive surgical margins are lower in patients with PSA density <0.25 when biopsy Gleason score is ≤6 or <0.15 when the biopsy Gleason score is 7.

In the Memorial Sloan Kettering Cancer Center series [4], patients with pT3 cancers had a higher percentage of positive margins with interfascial dissection than with intrafascial dissection. The authors explain this intriguing result by saying that “during the intrafascial dissection, the prostate capsule is bare of tissue only on the posterolateral aspect, therefore, the lower positive surgical margin rate of pT3 prostate sides treated with intrafascial dissection is related not only to patient selection but also to the fact that the location of extracapsular extension of prostate sides with negative surgical margins was away from the posterolateral aspect of the gland.” Even admitting this fact, interfascial dissection should not have a higher positive margin rate among pT3 cases but should be similar to that of intrafascial dissection. The location of tumours should be similar in both patient subgroups and, theoretically, tumour location by itself should not influence the positive margin rate significantly. Another way of explaining this phenomenon would be that most pT3 cases that underwent intrafascial dissection had just focal extracapsular extension and, on the contrary, pT3 cases operated by the interfascial technique were mainly tumours with established extracapsular extension, which were big enough to have positive margins despite having left part of the neurovascular bundle attached to the prostate. In future papers, we expect Dr. Guillonneau's team to discuss the potency preservation in these patients in whom partial neurovascular bundle preservation was performed. If partial neurovascular preservation offers just poor to moderate recovery of erectile function, complete neurovascular bundle resection instead of partial preservation might be more appropriate in the intermediate-risk patients to avoid positive surgical margins.

Be that as it may, it is clear that we need better nomograms to decide in which patients we can perform preservation of the neurovascular bundles. The location of tumours based on biopsy information is not accurate enough. In the report of Secin et al. [4], almost 30% of prostate sides that harboured cancer had a negative preoperative tumour biopsy. Magnetic resonance imaging was of little value in their experience as well [4]. Better imaging modalities are crucial to determine the exact location of cancer within the prostatic gland or at least of the main prostatic tumour and decide the best surgical technique. Some pT3 tumours if located laterally or anteriorly may allow preservation of the neurovascular bundles. On the other hand, pT2 tumours located near the capsule at the posterolateral edge of the prostate may benefit from partial neurovascular bundle preservation to avoid iatrogenic positive margins.

The way towards perfection is still long and by the time we have such accurate imaging modalities, surgery may no longer be the gold standard and other minimally invasive techniques might replace the different surgical options available today.

References

1. Cunéo B, Veau V. De la signification morphologique des aponeuroses perivesicales. J Anat Physiol. 1899;35:235–245.

2. Villers A, McNeal JE, Freiha FS, Bocon-Gibod L, Stamey TA. Invasion of Denonvilliers’ fascia in radical prostatectomy specimens. J Urol. 1993;149:793–798.

3. Martínez-Piñeiro L, Cansino JR, Sanchez C, Tabernero A, Cisneros J, de la Peña JJ. Laparoscopic radical prostatectomy. Differences between the interfascial and intra-facial technique. Eur Urol Suppl. 2006;5:331.

4. Secin FP, Serio A, Bianco FJ, et al.. Preoperative and intraoperative risk factors for side-specific positive surgical margins in laparoscopic radical prostatectomy for prostate cancer. Eur Urol. 2007;51:764–771.

5. Martínez-Piñeiro L, Cáceres F, Sánchez C, et al.. Learning curve of laparoscopic radical prostatectomy in an University Teaching Hospital. Experience after the first 600 cases. Eur Urol Suppl. 2006;5:914–924.

6. Kattan MW, Scardino PT. Prediction of progression: nomograms of clinical utility. Clin Prostate Cancer. 2002;1:90–96.

7. Partin AW, Mangold LA, Lamm DM, Walsh PC, Epstein JI, Pearson JD. Contemporary update of prostate cancer staging nomograms (Partin tables) for the new millennium. Urology. 2001;58:843–848.

8. D’Amico AV, Whittington R, Malkowicz SB, et al.. Pretreatment nomogram for prostate-specific antigen recurrence after radical prostatectomy or external-beam radiation therapy for clinically localized prostate cancer. J Clin Oncol. 1999;17:168–172

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