Imagine a world championship boxing match. The two contestants are different screening methods for prostate cancer (PCa). The winner will be crowned King of Screening.
In one corner stands the current reigning champion, PSA. He has managed to retain the title for decades. Although some have questioned his ability to land accurate punches, he’s still the king of detection. A few contenders, like the PCA3 urine test, have so far failed to knock him out.
In the opposite corner, stands a boxer who was initially seen as an upstart by urologists in the audience. His name is MRI. Although initially backed by radiologists, many urologists are starting to support him by blending him into their detection and diagnostic services. Although their fusion equipment somewhat compromises his strength, he appears to be gaining a following.
The two methods are duking it out over accuracy and, to a lesser extent, healthcare economy. Fans of PSA admit that the blood the test itself has false positives that lead to pointless biopsies and overtreatment, at least it’s universally available and cheap, and has saved many lives.
A new study favors MRI for screening
The issues of cost and lack of availability has been an obstacle to considering MRI as a stand-alone screening tool. However, it is increasingly valued for clarification following suspiciously high PSA results. A growing number of studies are persuasive evidence that doing an MRI scan before biopsy can significantly reduce the number of unnecessary biopsies because MRI can rule significant PCa in or out. This has a positive domino effect: if needless biopsies are avoided, not only does this save costs associated with post-biopsy side effects and potential repeat biopsies, more treatment dollars are saved as patients don’t need surgery or radiation—not to mention the money spent on managing treatment side effects.
Now there is also a way to conserve the costliness of time-consuming multiparametric MRI (mpMRI). It’s called biparametric MRI (bpMRI) because it uses only two instead of three parameters (imaging sequences). Thus, it’s a shorter scan and does not need the IV contrast agent required for the third parameter. It saves time and money—but can it perform PCa screening as well as PSA?
A new study was presented at the Nov. 27-Dec. 1 2022 RSNA (Radiological Society of North America) meeting. The research was conducted by a team from Seoul National University Hospital in Seoul, Korea. According to an RSNA news report, the researchers “… compared the performance of biparametric prostate MRI and PSA testing in a large paired-cohort study.” They drew data from the records of 1,793 men who had both PSA testing and bpMRI.
Their cut-off points for suspicion of PCa were PSA ≥ 3 ng/mL and/or a bpMRI PI-RADS score 3-5 or 4-5. Screening using PSA and bpMRI were compared for cancer detection rates, false positive rates, and positive predictive values (PPV or likelihood of significant PCa).
Out of the 1,793 men, 150 (8.4%) had a positive PSA test, which was significantly greater than the 62 men (3.5%) with PI-RADS 3-5 and 41 men (2.3%) with PI-RADS 4-5. Notably, PSA had higher false positive rates than MRI (7.4% vs. 2.4% for PI-RADS 3-5 and 1.2% for PI-RADS 4-5). For men who had a biopsy showing PCa, PPV for PSA was 36.5% compared with 58.8% for PI-RADS 3-5 or 87.5% for PI-RADS 4-5.
Thus, the researchers found that MRI screening had a significantly lower rate of false positives and a significantly higher positive predictive value than PSA screening. Regarding healthcare expenditures, they concluded that in spite of higher up-front scan cost, bpMRI screening was expected to reduce unnecessary costs related to diagnosis (biopsy and pathology).
In summary, if the Korean authors’ head-to-head comparison had been the championship boxing match, MRI would clearly have emerged with the coveted championship as the better screening method! At the Sperling Prostate Center, we believe it’s just a matter of time before the new King of Screening replaces PSA.
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.