PCA3 test, when should this be carried out?
Posted , 8 users are following.
In brief my partner has had 2 high PSA readings, both under 10 though and the 3rd most recent showed a 2 point drop. He is having a 3T MRI scan in a few weeks and consultant wants to do a biopsy following this. I have read about the PCA3 test and wondered if this should be done after MRI but before biopsy as it only shows cancerous cells if I am right. This would then eliminate the need for biopsy or definitely confirm that biopsy should go ahead. Urologist is an expert in this test but hasn't mentioned it. Would there be a reason for this?
has anyone had experience of this extra test and not then needed biopsy? thanks, Caz
0 likes, 30 replies
harveybronx caz11527
Posted
Hi caz,
I also researched and had a PCA3 test in March, 2013, two years before my mpMRI. I would say that the PCA3 test is also obsoleted by the mpMRI, except for people for whom the mpMRI is not available, for whatever reason. In fact, I would say that all these statistical marker tests are obsoleted by mpMRI, since the mpMRI is actually locating the PCa if it exists. And, the negative accuracy of the mpMRI is, apparently, very high. However, the positive accuracy is not diagnostic, which is why a biopsy is required after a positive mpMRI results (high piRAD result).
My PCA3 score was 31, which was in the range of uncertainty that rendered the test useless for me. A score of of >25 was positive; however, that came with an uncertainty of +-6, which means my situation could have been positive or negative for PCa. In any case, as my report indicated, the PCA3 cutoff of 25 results in a sensitivity of 77.5% and specificity of 57.1% for PCa. That's the problem with these statistical probability tests. I believe the mpMRI accuracy for negative aggressive PCa is in the very high 90s%, like 97% or so. I'll have to find the relevant article.
My PCA3 report also says: This assay [PCA3} is indicated for use in conjunction with other patient information to aid in the decision for repeat biopsy in men 50 years of age or older who have had one or more previous negative prostate biopsies and for whom a repeat biopsy would be recommended..."
Harvey
paul96555 harveybronx
Posted
Thanks, you have reassured me that my MRI wasn't a waste of time as could have cleared me as I learn from your post that it doesn't tend to give false negatives (so if it says you're fine, you are ... mine was 3T multi-parametric...). Wonder what its false positive rate is .... not giving false negatives is only useful if it actually gives a good few negatives !
harveybronx paul96555
Posted
Paul, From the mpMRI, the highest PI-RADs score is 5, which means:
PI-RADS 5: very high (clinically significant cancer is highly likely to be present)
Again, this is not diagnostic. It requires a biopsy. Since this is a statistic, it's meaningless to say that it was true or false when applied to a single individual. In any case, I haven't looked for the article that says what percentage of PI-RAD 5 actually turned up aggressive PCa after a biopsy. I don't think it really matters, because that percentage can't affect one's decision. Whatever it is, it's probably a high number.
Harvey
harveybronx paul96555
Posted
Paul, I just re-read an article reporting research performed in Germany, and published in 2013 soon after the PI-RADS (prostate imaging, reporting, and data system) was devised.
59 patients were in the study. I bolded, below, the answer to your question from that study. QUOTE: "In 28 patients (51 lesions) MR-guided in-bore biopsy was positive for tumor (Gleason grade 6 or higher). A cut-off limit of 10 or more points in summation of the individual scores of all three sequences was used, leading to a 90% sensitivity, 63% specificity, 58% positive predictive value, and 92% negative predictive value."
The technology has advanced since then, so it's probably more accurate now. There's now a version 2 of the PI-RADS.
Harvey
paul96555 harveybronx
Posted
>> that percentage can't affect one's decision
- well, depending what it is, it surely could. Suppose that (I am proving my point here using reductio ad absurdum) (this is synthesised, nonsense data to make my point) ..
.... suppose that 1. the MRI was 100% accurate in all of its negatives, also suppose that 2. 66% of men remitted for an MRI actually had no cancer, also suppose that 3. The MRI only gave a negative result for 0.01% of those remitted. Would you think it a good use of your time and money ? It would only be adding useful, significant data for a tiny minority. Clearly it must be vastly better than those stats, as it is well rated. I don't know the real stats. But logically, we must agree that those stats, if known, could matter.
NB did anyone in GB watch the news tonight, BBC main news, about the new P Ca treatment using seaweed extract injections activated by a laser in the vicinity of the in-situ P Ca. Cured 50% of men's P Ca with no side effects. I guess the other 50% it didn't work for, then had to go down the radiation, or prostatectomy, or watchful-waiting, routes. Which must have been disappointing for them, althought it's a good news story for sure. So far it's just been a trial of 300 men.
harveybronx paul96555
Posted
Hi Paul,
Maybe it wasn't clear. I was writing about PI-RAD 5, since that's the question I was asked, In that case it doesn't matter what the actual percentage is, because the developers of the system have determined that it's a very high percentage, whatever it is, so it's very likely that one has PCa, and it would be crazy to not have a biopsy.
Seaweed and laser--interesting!
Harvey
Harvey
paul96555 harveybronx
Posted
Thanks. Mine was a 4/5. Turned out to be clear. Googling I see that :
"...accuracy of mp-MRI for detecting Gleason grades 4 and 5 in the transitional zone was 79% for T2WI and 72% when combined with DWI and DCE MRI. For low-risk disease, the accuracy levels were 66% for T2WI and 62% when combined with functional imaging" - which sounds fairly good.