By: Dan Sperling, MD
The current “gold standard” for diagnosing suspected prostate cancer (PCa) is a transrectal ultrasound (TRUS) guided needle biopsy, usually performed with a topical or local anesthetic by a urologist in an office setting. The walnut-size prostate gland lies in a protected position against the bladder and in front of the rectal wall. The urethra, or tube that carries urine out of the bladder toward the penis, passes through the center of the gland. The neurovascular bundles (nerves and blood vessels) that are essential for erections “hug” the prostate on both sides. Because prostate biopsy is an image-guided invasive prostate procedure, several factors will influence the risk of side effects and the accuracy of the diagnosis. The purpose of this article is to summarize recently published literature on problems associated with TRUS biopsy.
The U.S. Preventive Services Task Force issued a 2012 statement recommending against broad PSA screening for prostate cancer, and encouraging physicians to discuss screening on a case-by-case basis with male patients. One of the reasons to discontinue screening was the number of men who underwent TRUS biopsies based on elevated, but nonspecific, PSA values. Depending on the study, on average roughly 50% of patients are negative for PCa (no cancer). A study by a Syrian team of researchers summarizes their four-year retrospective analysis of patients who had TRUS biopsies at their center because of suspicious PSA values.[i] There were 406 men biopsied, and 237 (58.4%) were diagnosed with PCa, whereas 166 (40.9%) were found to have benign prostatic hyperplasia (BPH) and 3 men were unable to be diagnosed due to biopsy collection errors. They concluded that “a high percentage of patients are undergoing unnecessary biopsy, which suggests that the performed screening tests had a high level of false positive and may need re-evaluation,” a view that supports the Task Force caution regarding nonspecific PSAs.
Most patients scheduled for a TRUS biopsy are likely to take for granted that the urologist is skilled at the procedure. However, as with all prostate procedures, there is a learning curve involved with reading/interpreting ultrasound, where to place the biopsy needles, and how to place them without hitting sensitive structures. A Spanish study examined 790 consecutive biopsies performed over a 3-year period by four different first year urology residents.[ii] Of the 300 biopsies that proved positive for PCa, the rate of accurate https://sperlingprostatecenter.com/prostate-cancer-detection/improved as each resident became more proficient, and the difference was statistically significant between the earlier and later results. Patients about to undergo a TRUS biopsy may want to be aware that the more experienced the urologist, the greater likelihood that the results will be accurate.
Erectile dysfunction (ED) after TRUS biopsy
The prestigious British Journal of Urology International published a report by Murray et al. (Aug. 2015) on the incidence of ED following TRUS biopsy. They enrolled 220 men in a prospective study of pre-biopsy sexual function, and their function afterward at intervals of 1, 4 and 12 weeks (all assessments using the International Index of Erectile Function 5-item questionnaire). Prior to biopsy, 38.6% reported no ED, 22.3% mild ED, 15.5% mild-to-moderate ED, and 13.6% severe ED. When compared with their questionnaire results following biopsy, the authors report that at 1, 4 and 12 weeks there were significant reductions in sexual function. They concluded, “The effects of TRUS-guided prostate biopsy on erectile function have probably been underestimated. It is important to be aware of these transient effects so patients can be appropriately counselled. The exact cause of this effect is yet to be determined.” In practice, it is probably safe to say that few patients are told in advance that TRUS biopsy entails a risk, however small, of ED for an indeterminate period.
Infection risk after TRUS biopsy
Antibiotics are routinely administered at the time of TRUS biopsy to prevent infection if bowel bacteria are introduced into the prostate and pelvic cavity. This has proven very effective, with infection occurring rarely. However, in a very small percentage of cases, infection is severe enough to warrant hospitalization. A study of 34,865 cases from Victoria, Australia sheds light on the incidence and cost of hospital admission due to TRUS biopsy.[iii] Within 7 days of biopsy, 604 patients (1.73%) were readmitted to the hospital for infection-specific causes, with median stay being 4 days. Over the 5 years of the study, the total readmissions were 3,686, with one patient in-hospital death related to infection. The authors write, “Infection following TRUS biopsy was associated with a readmission rate for infection of 1 in 57 biopsies, an excess of 3,686 bed days required over 5 years…”
Multiparametric MRI and MRI-guided targeted biopsy
Multiparametric MRI (mpMRI) offers two advantages over the diagnostic pathway of elevated PSA/TRUS biopsy. First, mpMRI has excellent sensitivity in detecting significant PCa, meaning disease aggressive enough to warrant biopsy and probably treatment; mpMRI can therefore rule the need for a biopsy in or out. Second, if a biopsy is indicated based on the MRI interpretation, an MRI-guided real-time biopsy, done in the bore (tunnel) of the MRI equipment, can greatly reduce the risk of infection or hitting critical structures while also increasing diagnostic accuracy. While a learning curve would still be involved for a radiologist in training, MRI-guided targeted biopsy is highly unlikely to put sexual function at risk, and greatly minimizes the risk of infection since the biopsy involves fewer needles than TRUS biopsy. Urologists are increasingly referring patients for mpMRI before any biopsy, a practice that represents a paradigm shift in prostate cancer biopsies.
[ii] Escudero-Fontano E, Juan-Escuder J, Nuño de la Rosa-Garcia I et al. Influence of learning curve in the diagnosis of prostate cancer by ultrasound guided biopsy. Arch Esp Urol. 2015 Jul;68(6):532-538.
[iii] Roth H, Millar JL, Cheng A, Byrne A et al. The state Of TRUS biopsy sepsis: readmissions To Victorian hospitals with TRUS biopsy-telated iInfection over 5 years. BJU Int. 2015 Jul 14. doi: 10.1111/bju.13209. [Epub ahead of print]