Focus of the Report: Transperineal template prostate (TTP) biopsy is an alternative to standard transrectal ultrasound (TRUS) biopsy for repeat biopsies. TTP biopsy is a form of saturation biopsy (at least 20 cores) that uses a brachytherapy grid to assure even distribution of the cores.
Technology Description: TTP biopsy differs from TRUS biopsy in 2 key ways: the route of needle insertion and the method of determining biopsy sites. The needle is inserted transrectally in TRUS biopsy procedures, while it is inserted through the perineum (the area between the anus and scrotum) in TTP biopsy procedures. The perineal approach avoids the risk of introducing rectal bacteria into the prostate gland, which can cause urosepsis, and allows sampling from the transition zone (area surrounding the urethra) and anterior portion of the prostate gland. In TRUS biopsy procedures, biopsy sites (typically 10-12) are selected randomly. TTP biopsy involves the use of a sterile, disposable template (i.e., a brachytherapy grid) through which the biopsy needles are inserted in a manner that assures uniform spacing. Both TTP biopsy and TRUS biopsy use a rectal ultrasound probe for visualization.
Controversy: Transperineal saturation biopsy offers a solution to the problem of expanding the number of biopsy cores by eliminating the need to pass the biopsy needle through the rectum. TTP biopsy is a form of saturation biopsy (defined as at least 20 biopsy cores). Other possible advantages of TTP biopsy over TRUS biopsy are the ability to extract cores from the transition zone and other anterior regions of the prostate, an even distribution of a large number of closely spaced biopsy samples throughout the 3-dimensional volume of the prostate, collection of more tissue with each core because the needle is parallel rather than perpendicular to the gland, the ability to confirm unifocal cancer, and reduced postprocedure pain. The disadvantages of TTP biopsy are the need for general anesthesia and thus both greater costs and longer procedure time, a requirement for greater expertise on the part of the clinician performing the biopsy, and an elevated risk of complications attributable to the greater number of cores.
Is TTP biopsy accurate in identifying cancerous lesions (clinical validity) in men whose prior biopsies have been negative?
Does the use of TTP biopsy change treatment decisions or improve health outcomes (clinical utility)?
How does TTP biopsy compare with transrectal prostate biopsy?
Is TTP biopsy safe?
Have definitive patient selection criteria been identified?
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