mpMRI, Probable Extracapsular Extension, and clinical Tumor Stage

[Longrunner]

My first mpMRI on February 3, 2022 showed a PiRads 5 Lesion.

A second read of this mpMRI at MSKCC showed Probable Extracapsular Extension of this lesion.

A repeat mpMRI was performed at MSKCC on August 17th with the same finding of PiRads 5 with Probable Extracapsular Extension. At MSKCC, Probable means 75% certainty of the radiologist's interpretation of findings.

Is Probable ECE on the mpMRI determinative of a clinical tumor stage of T3?

Thanks in advance for helping me understand how ECE is determined for staging and risk grouping.

[Tall_Allen]

Yes and no. According to AJCC staging criteria, stage T3 should only be given by the doctor who palpates the prostate (DRE). In the real world, however, it is often determined by MRI. This is problematic because there are many false positives on an MRI (whereas there are many false negatives with a DRE). In the following study, a positive MRI finding was only correct (positive predictive value - PPV) 47% of the time:

pubmed.ncbi.nlm.nih.gov/296...

Other schemes for detecting EPE have been suggested:

prostatecancer.news/2020/04...

[Longrunner in reply to Tall_Allen]

A 47% positive predictive value sounds like a coin flip of whether or not ECE exists. I don't think it is wise for me to place a bet on a false positive. Thank you TA for sending the article reference!

[Mike404]

I’m in a similar situation, though my odds of ECE are slightly less. I suggest getting a PSMA PET scan if possible. Mine ruled out metastatic disease, which leaves only local or microscopic metastatic potential.

The biggest impact is on treatment. The surgeon wanted to irradiate the prostate bed afterwards due to the possible ECE. The radiation oncologist will add ADT to the SBRT to both make it more effective and deal with cancers outside the prostate.

This led me to radiation plus ADT as the primary treatment. I didn’t see the point in side effects from surgery and radiation, with a possible triple play of ADT later. Depending on the odds of ECE and your risk, the length of ADT is the principle factor that needs to be determined.

[Longrunner]

Mike, I really appreciate your helpful response.

A second biopsy showed 3+4 (4% 4) in the Index Lesion. However, it might not matter since my Decipher Genomic Risk is high with a score of .63. The Doctors at MSKCC will sort this all out for me.

Up to now, there has been no mention of lymph node involvement or metastasis. Was there any prior testing that led you to get a PSMA PET scan?

[Mike404]

I did the PET scan because I had a reasonable suspicion (3 of 5) on the MRI of ECE. The lesion abutted the capsule. The PET scan was clear. I went with SBRT and six months ADT, which should make the radiation more effective and address any microscopic cells that escaped.

[Longrunner in reply to Mike404]

Thanks Mike for your reply. I saw Dr. Zelefsky at MSK last Thursday and will follow a similar treatment path of SBRT plus 6 months of ADT.

[Mike404]

Good luck! I finished my SBRT and am on my second month of ADT. No serious side effects so far. I did take Imodium the first day and had to get up three times to pee during the night, but that all quickly resolved. Minor “warm flashes” at night, but I wouldn’t have noticed if not primed for it. I do exercise daily.