European Urology

Onik G, Miessau M, Bostwick DG
J Clin Oncol 2009;27:4321–6
Experts’ summary:
To compare a new staging three-dimensional transperineal prostate mapping (3DTPM) biopsy method with traditional transrectal ultrasound (TRUS) biopsy and assess its possible impact on patient management, the authors studied 180 patients who had unilateral cancer on TRUS biopsy and were considering conservative management. These patients underwent restaging, with 3DTPM, carried out using a brachytherapy grid under TRUS guidance. Biopsies were taken every 5 mm throughout the volume of the prostate, with a median of 50 cores. Of the 180 patients, 61.1% were positive bilaterally and 22.7% had Gleason scores increased to 7 or higher. Thirty-six patients had negative results on 3DTPM. Complications of 3DTPM included 7.7% of patients experiencing acute urinary retention and 1% with haematuria.

The authors’ conclusion was that 3DTPM can be safely used to accurately stage prostate cancer (PCa) patients and could have a profound effect on patient management, because patient management is increasingly based on the extent and characteristics of PCa.
Experts’ comments:
Precise knowledge of tumour extent, grade, laterality, and multifocality is needed for the best management with treatment options such as surveillance or focal or whole-gland treatment. There are currently two techniques for obtaining this precise knowledge: 3DTPM, as shown by Onik et al, and targeted biopsies to prebiopsy multiparametric magnetic resonance imaging (MRI)–suspicious lesions, as shown by Lemaitre et al, Villers et al, and Hambrock et al. [1], [2], and [3]. These two techniques are still considered experimental in 2010 and are not available in all centres performing prostate biopsies, but they are increasingly being investigated. As a European urologist with access to recent modern imaging protocols, I am reluctant to use this 3DTPM technique studied by Onik at al and previously studied by Barzell et al. [4] routinely for several reasons:

• • Morbidity. 3DTPM leads to acute urinary retention and severe haematuria. It also includes mostly transient erectile dysfunction that might persist if the procedure is repeated, as in cases of surveillance protocols.
• • Sequelae. 3DTPM was suspected to induce fibrosis at the apex—biopsied 50 times—and to add difficulty in cases of nerve-sparing radical prostatectomy.
• • Time and costs. The procedure under general anaesthesia lasts longer for the patient and takes significantly more time for the urologist and pathologist than office-based TRUS biopsies. A prostatic biopsy procedure should be a fast, simple, well-accepted detection test, because it is frequently repeated. In most countries, there is no reimbursement for 3DTPM costs.
• • Quality of information. Because of gland swelling during the procedure, the precise location of each separate core is not optimal, even with the 5-mm grid template. The result gives cancer length in millimetres with no cancer volume or contours, as is provided with imaging. Clinical significance is based only on positive biopsy number and cancer length.
• • Overdiagnosis of insignificant cancers. The greater the number of biopsy cores, the higher the risk of diagnosis of cancer microfoci. This is the main drawback of this technique as a sustained biopsy protocol.

The strategy of targeted biopsies to an MRI-suspicious area has the potential to improve biopsy results, including detection of significant cancers, ruling out insignificant cancer, providing more informative sampling of cancer (length and grade on biopsy), and decreasing the number of biopsy cores required to obtain this information. This concept emphasised the use of MRI in PCa management [5], something that is controversial and a proposition that has little role to play in current guidelines. However, a consensus on the MRI protocol was reached: A diagnostic method that was more specific for clinically significant PCa would retain the beneficial effect of screening on mortality while minimising the problems of overdiagnosis and overtreatment. Imaging could be incorporated into the risk analysis and used as a triage tool in order to select men for prostate biopsy.

Conflict of interest

The authors have nothing to disclose.