Saturation biopsy, generally considered obtaining more than 20 biopsy tissue cores from the prostate in a systematic manner, has been proposed in the diagnosis (for initial or repeat biopsy), staging, and management of patients with prostate cancer.
Prostate cancer is a common cancer and is the second leading cause of cancer-related deaths in men in the U.S. While prostate-specific antigen (PSA) testing and digital rectal exam (DRE) can detect abnormalities, only a biopsy of the prostate gland can confirm a diagnosis of prostate cancer. Risk factors for prostate cancer include a persistent elevated PSA, and atypia and/or high grade prostatic intraepithelial neoplasia (PIN) on prior biopsy. For at-risk patients with a normal biopsy, questions exist about subsequent evaluation, since repeat biopsy specimens may be positive for cancer in a substantial percentage of patients.
In the early 1990s, use of sextant biopsies involving 6 random, evenly distributed biopsies became the standard approach to the diagnosis of prostate cancer. In the late 1990s, as studies showed high false-negative rates for this strategy (missed cancers), approaches were developed to increase the total number of biopsies and to change the location of the biopsies. While there is disagreement about the optimal strategy, most would agree that initial prostate biopsy strategies should include at least 10â€“14 cores. Additional concerns have been raised about drawing conclusions about the stage (grade) of prostate cancer based on limited biopsy material. Use of multiple biopsies has also been discussed as an approach to identify tumors that may be eligible for subtotal cryoablation therapy.
At present, many practitioners use a 12 to 14 core â€œextendedâ€ biopsy strategy for patients undergoing initial biopsy. This extended biopsy is done in an office setting and allows for more extensive sampling of the lateral peripheral zone; sampling of the lateral horn may increase the cancer detection rate by approximately 25%. (1)
Another approach to increase the number of biopsy tissue cores is use of the â€œsaturationâ€ biopsy. In general, saturation biopsy is considered as more than 20 cores taken from the prostate, with improved sampling of the anterior zones of the gland, which may be under-sampled in standard peripheral zone biopsy strategies and may lead to 17% of cancers being missed, according to one study. (2) Saturation biopsy may be performed transrectally or with a transperineal approach; the transperineal approach is generally performed as a stereotactic template-guided procedure with general anesthesia.