Did your doctor say it’s time for a biopsy, based on your PSA results? Do you shudder at the idea? How do you know you really need to have 12+ randomly placed needles throughout your prostate gland?
The answers to these questions can be found in a Swedish paper published online July 9, 2021 by the respected New England Journal of Medicine. What’s particularly exciting about this study by Eklund, et al.[i] is its randomized design involving 12,750 men eligible for prostate cancer (PCa) screening.
Let’s talk about PCa screening
Cancer screening is good, right? It offers the best odds for successful treatment. Mammograms detect early breast cancer; colonoscopies find early colon cancer; annual skin exams identify early melanoma—these screenings and more result in statistics showing that early detection saves lives.
The problem with PSA screening for PCa is the prostate specific antigen test itself. An abnormally high or rising PSA doesn’t necessarily mean you have PCa. Many conditions can bump up the amount of PSA circulating in the blood, but doctors recommend a biopsy just to be on the safe side.
Screening vs. diagnosis
The PSA screening test is NOT a diagnosis. A biopsy is the only sure way to diagnose PCa because the actual cancer cells, if present, are visible under a microscope. Did you know that a million TRUS prostate biopsies are done annually in the U.S.? Most of them are the result of PSA screening.
Unfortunately, these conventional TRUS biopsies do not give enough accurate diagnostic information to plan successful treatment. They often find insignificant PCa that may not require immediate treatment; conversely, in certain gland locations they can miss significant PCa that poses a death risk. The result? Many patients with insignificant disease have had their PCa clobbered by treatments that left them with urinary and sexual side effects, while other patients harboring aggressive disease have gone on Active Surveillance even as the silent killer in their body spread and became incurable.
Multiparametric MRI: a better screening tool
The population-based Eklund study recruited participants by mailed invitations to men 50-74 years old in the general population. Enrollees with PSA levels ≥ 3 ng/mL were randomly assigned to either have a conventional TRUS biopsy or to have multiparametric MRI (mpMRI). If the MRI results suggested PCa, the men then had an MRI targeted biopsy as well as a standard TRUS biopsy. The authors write, “The primary outcome was the proportion of men in the intention-to-treat population in whom clinically significant cancer (Gleason score ≥7) was diagnosed. A key secondary outcome was the detection of clinically insignificant cancers (Gleason score 6).” Basically, can MRI screen for PCa before biopsy?
In structuring a head-to-head comparison of standard TRUS biopsy (based on PSA alone) vs. MRI-targeted biopsy plus TRUS biopsy (based on MRI-detected suspicious lesions), the researchers were exploring whether imaging can add a further layer of PCa screening before biopsy. Since the blood test is not specific, will MRI indicate if an individual with a suspicious PSA really needs to have 12+ randomly placed needles throughout your prostate gland?
The team found that the two biopsy approaches produced roughly comparable results regarding detection of clinically significant disease:
- TRUS alone diagnosed clinically significant PCa in 18% of cases
- MRI-targeted biopsy protocol diagnosed clinically significant PCa in 21% of cases
Since the numbers differed by only 3%, the authors defined the MRI-targeted biopsy as non-inferior to TRUS biopsy in diagnosing clinically significant cancer. However, “Ignoring the supplemental standard biopsy, the MRI-targeted biopsy alone in the experimental biopsy group reduced the detection probability of significant cancer to 17% …” thus dispelling the non-inferiority status. Put another way, MRI-targeted biopsy alone is superior to standard TRUS biopsy at detecting clinically significant PCa, while diminishing the risks of TRUS biopsy.
The MRI-targeted biopsy protocol also outperformed TRUS biopsy in diagnosing clinically insignificant cancers that don’t require biopsy:
- TRUS rate of diagnosing clinically insignificant PCa was 12%
- MRI-targeted biopsy protocol rate of diagnosing clinically insignificant PCa was 4%.
As reported in a medical news story, “Among men with elevated PSA levels and positive results on MRI exam, using the combined biopsy approach reduced by 64% the number of clinically insignificant tumors identified compared with the standard biopsy approach alone.”[ii]
Safer, more effective screening using MRI
The authors bemoan the lack of broad PCa screening programs due to the high rates of overdiagnosis and unnecessary biopsies based on PSA alone. To address this dire state that puts men at risk by failing to screen, their study offers a solution in the form of safer, more effective MRI screening:
We showed, in a population-based, screening-by-invitation trial, that detection of clinically insignificant tumors and benign findings on biopsy were lower (by 64% and 74%, respectively) among men with elevated PSA levels … when biopsy was performed only in men with positive MRI results … These results were achieved without compromising detection rates of clinically significant cancers. In addition, fewer infections after the biopsy procedure were noted in the experimental biopsy group than in the standard biopsy group…
The Sperling Prostate Center extends congratulations and thanks to the Eklund team. In justifying the addition of mpMRI to PSA screening protocols, they have added valuable data to this growing trend.
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] Eklund M, Jäderling F, Discacciati A, Bergman M, Annerstedt M et al. MRI-Targeted or Standard Biopsy in Prostate Cancer Screening. N Engl J Med. 2021 Jul 9. doi: 10.1056/NEJMoa2100852. Epub ahead of print. PMID: 34237810.
[ii] Yee, Kate Madden. “MRI for prostate cancer screening reduces unnecessary biopsies.” AuntMinnie.com, July 12, 2021. https://www.auntminnie.com/index.aspx?sec=sup&sub=mri&pag=dis&ItemID=132873