"I am not saying that G 6 can metastasize -- it can not -- however, some men with G6 progress and develop higher-grade lesions, and those can metastasize."
In an important Decipher study, of men with G6 (3+3) and pT2 confirmed at biopsy, 10% had a high-risk Decipher score and 26% an intermediate score. For G6 and pT3a, it went to 16% high and 20% intermediate. This is why men contemplating AS are having genomic tests like Decipher Biopsy or Oncotype. about
50% of men leave AS for treatment. L. Klotz, the big AS proponent said "...the estimate is that 1%–2% of patients per year will undergo grade progression."