Genomic tests like Decipher can aid a decision about
adjuvant therapy after RP in borderline cases, such as some G8's. But it is also useful for setting an approximate PSA "trigger point" for early or very early salvage RT.
While genomics can help in some AS vs. treatment decisions, note that the Decipher Biopsy report itself states that the concordance between the test done on biopsy vs RP tissue is 70%. This is probably because biopsies can miss the most serious lesion. One poster on another forum related that her husband's biopsy Decipher was low risk, but given adverse features after RP they wanted it repeated on RP tissue. It came back high risk! (I would think a downscoring is fairly uncommon.) So if you are planning surgery, it's better to wait and test RP tissue.
The Decipher test is run twice on two different tissue samples and the higher score of the two is reported to you. It does not look at your Gleason score, staging, or any adverse features of your RP path report. It is based entirely on the RNA profile of your PCa.
There is a free GRID report that you can request with your Decipher report. It has a good deal of interesting information about
your specific PCa, including theoretical response to ADT, RT, one chemo drug, and one immunotherapy drug. While the GRID data, unlike the Decipher score, has not been validated for making clinical decisions, it is worth requesting.
I inquired with GenomeDx after I got my GRID report, and they confirmed that over time they might change the algorithms that generate the various GRID scores. They have one's test result (genetic analysis) on file and can rerun the GRID report at any time free of charge. So if I encounter BCR in the future, I'll request another GRID report, since my scores might change. (The Decipher test has already been validated, so your Decipher score itself -- your risk for metastases -- most likely won't change anytime soon).
To see the distribution of 5-year metastasis-risk scores (low, intermediate, high) for your Gleason score + pT staging, see Table 2 inDecipher correlation patterns post prostatectomy: initial experience from 2342 prospective patients