MRI Outperforms PHI for Patients Considering Active Surveillance

When it comes to Active Surveillance (AS) decisions, there’s good news and bad news. The good news: based on biopsy results, more doctors are recommending AS for prostate cancer (PCa) patients with insignificant disease. The bad news: the biopsy might have missed significant PCa so the patient can’t know for sure if AS is a safe decision. For example, in one study of 300 patients who all had radical prostatectomy within 6 months of biopsy, almost half (46.7%) of “biopsy-proven” Gleason 3+3 patients were upgraded to 3+4 or 4+3 based on their surgery results.

Let’s talk about insignificant vs. significant PCa. Dr. Jonathan Epstein (Johns Hopkins) defines insignificant PCa as organ-confined, tumor volume < 0.2cm3, Gleason score < 6, and:
• Clinical stage T1c
• PSA density <0.15ng/mL
• No Gleason 4 or 5
• Fewer than 3 positive cores (from 6)
• <50% cancer per core
Whether Gleason 3+3 is capable of becoming more aggressive is a subject of much debate. Until it’s resolved, it’s my current position that even low-risk PCa is still cancer and has the potential to progress. On the other hand, significant PCa is more dangerous. “Significant” means a tumor with at least one Gleason 4 value on biopsy. Gleason 4 PCa has the capacity to grow, increase in aggression, and spread outside the gland. In other words, it increases PCa mortality risk.

Back to the AS decision. As we saw from the study I mentioned, standard 12-core TRUS biopsies can miss significant cancer. So how can patients know if they are really AS candidates? To find out if multiparametric MRI (mpMRI) or other test could predict significant PCa, another research team looked back at the clinical findings of 120 patients who were eligible for AS (based on biopsy) but chose radical prostatectomy instead. They compared the predictive performance of mpMRI vs. the Prostate Health Index (PHI) blood test in patients who seemed eligible for AS. All the men in their study had multiparametric MRI, the PHI test and a prostate biopsy prior to radical prostatectomy. After surgery, the lab analysis of the removed glands showed that 45.8% of the patients had higher grade tumors than what was found on biopsy. (This is very similar to the 46.7% upgrading on the earlier study.) All surgical results could then be compared with what the biopsy, PHI and mpMRI predicted about significant PCa.

They found that mpMRI was 73% accurate in excluding significant cancer, meaning that those men could safely have gone on AS. When they computed PHI and mpMRI into their own predictive model (which also included the PCA3 urine test), mpMRI “had the highest net benefit.” Therefore, patients considering AS based on a biopsy of Gleason 3+3 can gain greater reassurance of the safety of that choice by scheduling an expert multiparametric MRI on a 3T magnet, such as we offer at our Center.

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

[1] D’Elia C, Cerruto M, Cioffi A, Novella G et al. Upgrading and upstaging in prostate cancer: From prostate biopsy to radical prostatectomy. Mol Clin Oncol. 2014 Nov; 2(6): 1145–1149.
[2] Porpiglia F, Centiello F, De Luca S, Manfridi M et al. In-parallel comparative evaluation between multiparametric magnetic resonance imaging, prostate cancer antigen 3 and the prostate health index in predicting pathologically confirmed significant prostate cancer in men eligible for active surveillance. BJU Int. 2016 Oct;118(4):527-34.