Prostate biopsy: will transperineal replace transrectal?

The Ginsburg study group is a multidisciplinary international collaboration of interested parties in the diagnosis of prostate cancer. Their publication in this issue of the BJUI addressing transperineal prostate biopsy is a reflection of the growing interest in this approach as an alternative to the transrectal route 1. Whilst local anaesthetic and antibiotic use have made transrectal prostate biopsy a relatively straightforward outpatient procedure, it is not without significant limitations in terms of patient acceptability, concerns regarding safety and potential for underdiagnosis. Contemporary data concerning the outcomes of transrectal biopsy are available from 1000 participants in the ProtecT study 2. Fever was reported in 18% of men, and 1.3% of men were admitted to hospital. A fifth of men stated that having a further biopsy would be a moderate or major problem, largely because of pain and infective complications – an important statistic in view of the quoted 38% rebiopsy rate within 5 years. A recent focus group at our unit highlighted patient concerns with the uncertainties associated with transrectal biopsy: a negative result is commonly misleading and the misclassification of low-risk disease may lead to the undertreatment of a third of men or overtreatment of the remainder 3. Urosepsis after transrectal biopsy is becoming more of an issue as a result of increasing numbers of quinolone-resistant strains of organisms in bowel flora 4. Strategies to avoid this, however, appear to revolve around pre-biopsy rectal swabs and the identification of resistant microbes. Unfortunately, the lack of satisfactory levels of tissue penetration by alternative antibiotics, such as co-amoxiclav, render them relatively ineffective at preventing urosepsis even when caused by sensitive organisms 5. The transperineal approach offers a logical alternative. Needles pass through cleaned and prepared skin rather than bowel or faeces and so sepsis is almost completely eradicated. Comprehensive access to the prostate is gained particularly anteriorly and at the apex where transrectal biopsies may miss significant tumours 3. It would seem sensible, therefore, to offer primary prostate biopsy as a transperineal procedure in order to minimize the risk of infective complications and to provide a higher degree of confidence particularly to men likely to have no or low-risk disease diagnosed. What, then, are the downsides? From a safety point of view, template mapping protocols that sample a high number of cores are associated with rates of urinary retention of ∼10%, commonly avoided by the use of a urinary catheter. The limitation of the number of cores (24–40) and avoidance of peri-urethral tissue, as well as judicious selection of patients, appears to reduce this complication considerably (Chang et al., BAUS 2012 presentation). A general anaesthetic is usually required, although a spinal or local block may also be effective. One would expect the majority of men undergoing biopsy, particularly in a screened population, to have a relatively fit status from an anaesthetic point of view. Although local anaesthetic transrectal biopsies were well tolerated by the patients in our focus group, all stated they would prefer a general anaesthetic option. There is also the concern of ‘overdiagnosis’, but perhaps the focus should be on reducing overtreatment: low-risk disease from a transperineal biopsy is arguably more reassuring than an inconclusive transrectal biopsy, and allows the avoidance of radical treatment options with a higher degree of confidence, and from a single initial procedure 3. Further, the transperineal approach lends itself to the targeting of significant MRI lesions, whilst avoiding the insignificant ones 6. Alternative resources are required: the outpatient clinic must be replaced with theatre capacity and a ‘stepper unit’ is required. The histopathology resources may be offset, at least in part by limiting core numbers and reducing repeat biopsies. If the safety and diagnostic benefits of transperineal biopsy are justified, professionals must determine how to best use these resources in order to allow extended choice to our patients. The optimum biopsy strategy in terms of diagnosing significant prostate cancer has yet to be determined but looks likely to involve transperineal sampling along with the use of information from multiparametric MRI. Collaborations such as that of the Ginsburg group will allow analyses of large datasets and inform our future practice. None declared.