Originally published 6/2/2016
Here’s a quote that sums up the issue with a TRUS (transrectal ultrasound) guided prostate biopsy: “Needle biopsy of the prostate is an invasive procedure, which can be associated with complications (including bleeding, pain, and infection) and it is therefore important to maximize the diagnostic information gained.”[i] The word “maximize” would be troubling if it meant sampling as many areas as possible. That scenario is what turns the prostate into a human pincushion, as the original blog below describes. Since we posted that 2016 blog, real-time MRI-guided targeted biopsy has begun to emerge in published studies as superior for maximum diagnostic accuracy while using the fewest needles. In fact, the combination of MRI before biopsy plus real-time MRI targeted biopsy not only avoids biopsy altogether for patients who don’t need it, it also excels at identifying Grade Group 2 (GG2) or greater prostate cancer (PCa) which is considered clinically significant and therefore requires a biopsy.
Five years since we posted the pincushion blog, the 2021 published results of a randomized clinical trial comparing MRI targeted vs. systematic TRUS biopsy show competitive detection rates of significant prostate cancer (PCa) for MRI targeted biopsy (35%) vs. TRUS systematic biopsy (30%). While this may not seem like a huge difference, notice a key benefit of MRI before biopsy: in a randomized clinical trial of 453 men, “A total of 79 participants in the MRI arm (37%) avoided a biopsy, and diagnosis of grade group 1 PCa was reduced by more than 50%.”[ii]
In other words, the anti-pincushion approach of using MRI to identify ≥ GG2 disease offers a way out of the overdetection and overtreatment of insignificant disease by targeting a minimum number of needles into the MRI-revealed areas likely to harbor the most dangerous PCa cells. There’s no excuse for puncturing the prostate with 12 or more scattershot needles when a safer, more accurate MRI-targeted biopsy is now available.
It wasn’t so long ago when the standard transrectal ultrasound-guided (TRUS) biopsy involved only six needles. It was called a sextant biopsy based on the Latin word sextans, meaning “a sixth.” As time would prove, it missed more than 40% of prostate tumors because it was essentially blind and random. To correct the problem, the number of needles rose to 10, then 12. Many urologists preferred to take 14 samples, and a “saturation” TRUS biopsy consisted of 20-24 needles. With all the variance, the walnut-sized prostate gland essentially became the human equivalent of a pincushion.
Since prostate tumors can’t be seen with ultrasound, it makes sense that the way to improve the odds of capturing prostate cancer is to increase the number of needles. However, doing so also raises the probability of biopsy-related side effects such as infection, prostatitis (inflammation), erectile dysfunction, urinary bleeding and rectal bleeding. A recent study reported one research team’s efforts to find the “optimum” number of needles that would maximize cancer detection while keeping risks to a minimum.[iii] The study involved 180 patients whose elevated PSA and/or abnormal digital rectal exam (DRE) were suspicious for prostate cancer. They were randomly assigned to one of three groups: Group A had sextant biopsies, Group B and 12-core biopsies, and Group C had 18-core biopsies. The team compared the rates of cancer detection and post-biopsy infection/prostatitis among the 3 groups:
The authors concluded, “The best balance between detection rate of prostate cancer and infectious complications of biopsies achieved in twelve-core biopsy protocol. Twelve-core biopsy enhances the rate of prostate cancer detection with minimum adverse effects.” My gut reaction is OUCH!
At our Center, we offer in-bore MRI-guided targeted biopsy instead of TRUS biopsy. Real time MRI guidance has unquestionable superiority over TRUS biopsy. Using a minimal number of needles, detection rates are at least 60%[iv]. Because of the reduced number of needles, infection/prostatitis risks are very low. MRI guidance ensures that the nerve bundles that control erection are not compromised by the biopsy needles, and we can avoid hitting the urethra. The prostate gland is not a pincushion, but living tissue with an important purpose. We make every effort to take the best possible care of that tissue, just as we respect and care for the whole person.
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.
[i] Giganti F, Moore CM. A critical comparison of techniques for MRI-targeted biopsy of the prostate. Transl Androl Urol. 2017 Jun;6(3):432-443
[ii] Klotz L, Chin J, Black PC, Finelli A et al. Comparison of Multiparametric Magnetic Resonance Imaging-Targeted Biopsy With Systematic Transrectal Ultrasonography Biopsy for Biopsy-Naive Men at Risk for Prostate Cancer: A Phase 3 Randomized Clinical Trial. JAMA Oncol. 2021 Apr 1;7(4):534-542.
[iii] Ghafoori M, Velayati M, Aliyari Ghasabeh M et al. Prostate Biopsy Using Transrectal Ultrasonography; The Optimal Number of Cores Regarding Cancer Detection Rate and Complications. Iran J Radiol. 2015 Apr 22;12(2):e13257. doi: 10.5812/iranjradiol.13257.
[iv] Arsov C, Rabenalt R, Blondin D, Quentin M et al. Prospective Randomized Trial Comparing Magnetic Resonance Imaging (MRI)-guided In-bore Biopsy to MRI-ultrasound Fusion and Transrectal Ultrasound-guided Prostate Biopsy in Patients with Prior Negative Biopsies. Eur Urol. 2015 Oct;68(4):713-20.