Lot of time on my hands so my thoughts started to dwell on Genomic testing
A year and a half ago Oncotype had me at "very low risk cancer " now Decipher genomic test shows high risk. I suppose cancer can change over a year and half but still Gleason score of 6 it is confusing.
Wonder how accurate they are?
Glen, perhaps I can shed a bit of light on a couple of concepts. First, the notion that all (and only) high-grade (Gleason) lesions are high risk for metastases has been dispelled by genomic testing. This was shown in a seminal 2016 study of Decipher results broken down by Gleason score and by pathological staging:Decipher correlation patterns post prostatectomy: initial experience from 2 342 prospective patients
(2016, Full Text)
Looking at the results there for G6 men who, after surgery, were confirmed as having prostate-confined cancer (pT2), 74% of the men had Decipher results that were low-risk for metastases; 26% were intermediate risk; and 10% were high-risk. For the G6 men who had cancer that grew through the prostate capsule, the high-risk percentage went up to 16%. If you look at Table 2, you will see that for each and every combination of Gleason score and path staging, there are men who are low, intermediate, and high risk (although the size of each group does vary in the directions you would assume).
(At the other end of G scores, my Decipher result on my RP tissue was, encouragingly, low-risk for mets even though I was G9 (4+5) on my final path report.)
As Mumbo mentioned, the G score reported from a biopsy is only as accurate as the highest-grade lesion that was sampled by any biopsy core. That is one reason many men have their G score upgraded after surgery. The biopsy samples a tiny amount of prostate tissue -- it can come back negative even when cancer is present, and it can underestimate the grade of the worst lesion(s) present somewhere in the prostate. As we know, G6 lesions cannot
metastasize; however, higher-grade lesions can arise ex novo elsewhere, and it's thought that G6 lesions can progress -- in other words, when the cancer cells divide, a cell of a higher G grade can arise resulting in a lesion clone with grades >6, which can
Just as a biopsy can miss higher-grade lesions, a genomics test relies on the company testing a tissue sample with the worse score. The Decipher test, for example, is run on different cancer samples and the higher (worse) score is reported to you. On another Forum, one fellow got a low-risk Decipher result on his biopsy sample. After his surgery, tissue was again submitted for the Decipher test and came back high risk! Nothing changed in the guy's cancer in the time interval -- rather the biopsy sample evidently missed a worse lesion. The Decipher Biopsy report itself states that the Decipher Biopsy risk category will match the Decipher RP risk category (only) 70% of the time.
That, unfortunately, is the nature of sampling and testing.
Hope that helps,