The entertainment value of a good suspense movie lies in keeping the audience guessing. Is the bad guy actually dead? Has the evil ghost actually left the haunted house for good? Why is the possessed person’s head still spinning if the demon was actually cast out? Moviegoers who are into such films happily pay for a ticket to be kept dangling while their hearts race. They know that, in the end, the hero triumphs and the threat is truly gone.

On the other hand, a patient with prostate cancer (PCa) who decides to be treated with a radical prostatectomy (RP) does not want to be kept guessing. Is all the cancer gone, or isn’t it? There is no entertainment value in being kept dangling for months or years after RP, only to find out that your PSA has risen above zero. This is called biochemical recurrence (BCR). It means a rising biomarker called prostate specific antigen is telling you that the threat was never really gone to begin with.

What if it can be known ahead of time that a patient is at high risk of BCR after surgery? Wouldn’t he and his doctor discuss alternative strategies? This problem has driven the search for a risk predictor that could help with treatment planning.

In fact, such a tool exists. It’s called CAPRA-S (Cancer of the Prostate Risk Assessment post-Surgery). It was designed over 10 years ago to improve on a previous easy-to-use CAPRA scoring method. However, the earlier method lacked accuracy because it was based only on pre-surgical clinical factors (patient age, PSA, biopsy Gleason score, clinical T stage, and percent of positive biopsy cores), so if CAPRA underestimated the risk, there were unpleasant BCR surprises down the line.

Therefore, to gain better accuracy, the designers of the CAPRA-S score integrated additional information from hundreds of post-surgical prostate specimens, or pathology. The added factors included:

• Gleason score from the actual gland specimens
• Surgical margin status
• Presence or absence of extracapsular extension (ECE)
• Seminal vesicle invasion (SVI)
• Lymph node involvement (LNI).^[i]

By combining all the data from case records, the developers were able to create a more accurate risk calculation based on a richness of factors, yet it was still as simple as easy to score as the original.

Now, a research team out of the National Cancer Institute has essentially challenged CAPRA-S to a duel. The other duelist is a new, MRI-based predictive tool based on real-time imaging results instead of post surgical pathology.^[ii] The challenge is, can a pre-treatment MRI staging of a patient’s PCa perform with the same accuracy as CAPRA-S? For their study, the authors included 604 PCa patients who had MRI before RP. Their scan results were evaluated for EPE and SVI, and subsequently correlated with their RP pathology in order to develop statistical patterns. In addition, 374 of the patients whose pre-treatment biopsy Gleason grade and RP pathology were available were evaluated using CAPR and CAPRA-S. Then, the two predictive models (MRI vs. CAPRA/CAPRA-S) were compared for accuracy in terms of actual follow-up rates of BCR.

The authors concluded, “Pre-surgical MRI-based staging features perform comparably to post-surgical pathologic staging features for predicting BCR. … MRI staging can pre-operatively identify patients at high BCR risk, helping to inform early clinical decision making.”

This is good news for PCa patients who are contemplating surgery. Everyone hopes for a “Hollywood ending” in which the surgery is success and they live happily ever after. Knowing in advance that they are or are not at high risk for BCR can help their personal “documentary” from turning into a suspense film with a surprise unwanted outcome. In fact, at Sperling Prostate Center, for patients who are interested in a focal therapy like Focal Laser Ablation, TULSA-PRO or Exablate MR guided Focused Ultrasound, pre-treatment multiparametric MRI can establish if they are good candidates.

When it comes to treatment planning for any stage PCa, MRI can enlighten decision-making by providing scene-by-scene accuracy.

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.

References

[i] Cooperberg MR, Hilton JF, Carroll PR. The CAPRA-S score: A straightforward tool for improved prediction of outcomes after radical prostatectomy. Cancer. 2011 Nov 15;117(22):5039-46. doi: 10.1002/cncr.26169
[ii] Merriman KM, Harmon SA, Belue MJ, Yilmaz EC et al. Comparison of MRI-Based Staging and Pathologic Staging for Predicting Biochemical Recurrence of Prostate Cancer After Radical Prostatectomy. AJR Am J Roentgenol. 2023 Jul 5.