By Brian J. Moran, MD
Today, approximately 240,000 men will be diagnosed with prostate cancer. There remains a large group of patients, however, that are undiagnosed with this disease despite having had transrectal prostate biopsy. It is not uncommon for an individual to have a rising PSA level despite having had negative prostate biopsies where no carcinoma was identified. Stereotactic Transperineal Prostate Biopsy (STPB) uses a perineal approach, where the needles are placed through the skin below the scrotum and in front of the anus, to obtain specimens from the prostate. Ultrasound guidance is used and the patient is anesthetized at the time of the procedure.
This technique has many advantages, the first of which is its increased ability to identify occult or “hiding cancers”. Our research and the research of others have clearly demonstrated that the transrectal biopsy does miss a significant percentage of cancers that occur in the anterior or front portion of the prostate. Our data in over 2,200 patients suggests that as high as 40% of patients are thought not to have malignancy, but indeed do have malignancy. Our group has previously published this information in Urology and the Journal of Urology. The second advantage to having a prostate biopsy using the perineal approach is that the infection rate is essentially 0%. This is simply because the rectal wall or rectum in general is not penetrated by the biopsy needle. As we know, infection is not uncommon after transrectal prostate biopsy and unfortunately the bacteria that are currently being identified have significant resistance to commonly used antibiotics. Our initial experience using STPB was confined primarily to patients who were diagnostic dilemmas in that they had persistent elevation of PSA level, while the biopsies were negative. More and more commonly today, patients are requesting perineal biopsy as their initial biopsy technique. This is because they have learned of the mapping ability using this procedure.
Specifically, the STPB is able to accurately identify the location within the prostate from which the cancer was obtained. This has dramatic implications because one is then allowed to apply therapy to only the area of malignancy, while avoiding normal sections of the prostate gland that have been proven NOT to contain malignancy. A whole new field of oncology will soon appear, and that is the realm of focal therapy for prostate cancer. Finally, due to the comprehensive information that STPB establishes, one is able to make a decision as to whether watchful waiting is a viable option. Watchful waiting is NO treatment of the cancer. Certainly this option is pursued by many individuals, however, with information based solely on transrectal prostate biopsy, one risks the possibility that a higher grade malignancy may also exist in the gland that was not identified. For these reasons, we think that STPB will definitely have a place in the future of prostate cancer diagnostics and therapeutics. With regard to prostate seed implants (brachytherapy), based on perineal biopsy data, there is no question that the implants today are much more sophisticated than those based on transrectal biopsies in the past.