You may be interested in Epstein's recent comments on the issue of whether to call GS 3+3 cancer vs."indolent lesion of epithelial origin" (ILE) as some doctors have proposed:
it has been questioned whether Gleason score 3 + 3 = 6 should retain the designation of cancer or be relabeled as indolent lesion of epithelial origin to avoid fear and consequential overtreatment of a proportion of potentially indolent prostate cancers. This is also based on the observations from the two studies showing that using a contemporary grading approach, pure Gleason score 3 + 3 = 6 at RP is incapable of regional lymph node metastasis. At RP, pure Gleason score 3 + 3 = 6, organ-confined, margin- negative disease has an excellent prognosis, with only occasional men demonstrating detectable prostate-specific antigen that may be in part due to the presence of benign glands at the margin and the use of ultrasensitive methods.
From a pathologist’s viewpoint, Gleason score 6 is still cancer, with many of the same morphologic and even molecular features of higher-grade cancer, a lack of a basal cell layer, and the potential to locally invade. Furthermore, whereas pure Gleason score 3 + 3 = 6 cancer at RP may be associated with a favorable clinical course, when present on biopsy, upgrading at RP can be seen in 17% to 36% of cases. Renaming Gleason score 3 + 3 = 6 cancer as an indolent lesion of epithelial origin tumor on biopsy carries the risk that patients on active surveillance will not adhere to long-term follow-up because they have been told they do not have cancer.
I think Epstein makes some very good points. GS 3+3, while it can't metastasize, can invade locally. This is similar to basal cell skin cancer, which left unchecked, can eat its way down farther even if it can't metastasize. I'm not saying it will eat into surrounding tissue, only that the potential is there. He is also right that we can't predict which GS 3+3 will always remain GS 3+3 and which will progress to higher grades - but that's exactly what active surveillance is all about
Upgrading due to biopsy "misses" can occur in a minority of cases, 17-36%. Of course, that's exactly what active surveillance does so well - it continually re-checks for higher grade cancer, especially with mpMRI targeting.
Whether calling it "cancer" or "ILE" will lead to more men choosing active surveillance, or to better or worse adherence to AS protocols, has never been tested. I think it's worth testing, and it should be fairly easy to test the two alternatives. It continues to puzzle me that famous researchers like Epstein haven't seen fit to do so. He, of all people, should be standing up for evidence-based medicine.